feat: Add "deno doc" subcommand (#4500)

18 files changed, 3233 insertions, 4 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 6a178bf03..ca7a0a367 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -493,6 +493,10 @@ dependencies = [
  "serde_derive",
  "serde_json",
  "sourcemap",
+ "swc_common",
+ "swc_ecma_ast",
+ "swc_ecma_parser",
+ "swc_ecma_parser_macros",
  "sys-info",
  "tempfile",
  "termcolor",
diff --git a/cli/Cargo.toml b/cli/Cargo.toml
index 1483324bf..acabcf7d0 100644
--- a/cli/Cargo.toml
+++ b/cli/Cargo.toml
@@ -63,9 +63,14 @@ webpki-roots = "0.19.0"
 walkdir = "2.3.1"
 warp = "0.2.2"
 semver-parser = "0.9.0"
+# TODO(bartlomieju): make sure we're using exactly same versions
+# of "swc_*" as dprint-plugin-typescript
+swc_common = "=0.5.9"
+swc_ecma_ast = "=0.18.1"
+swc_ecma_parser = "=0.21.8"
+swc_ecma_parser_macros = "=0.4.1"
 uuid = { version = "0.8", features = ["v4"] }
 
-
 [target.'cfg(windows)'.dependencies]
 winapi = "0.3.8"
 fwdansi = "1.1.0"
diff --git a/cli/doc/class.rs b/cli/doc/class.rs
new file mode 100644
index 000000000..635fd585a
--- /dev/null
+++ b/cli/doc/class.rs
@@ -0,0 +1,207 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use serde::Serialize;
+use swc_common;
+use swc_common::SourceMap;
+use swc_common::Spanned;
+use swc_ecma_ast;
+
+use super::function::function_to_function_def;
+use super::function::FunctionDef;
+use super::parser::DocParser;
+use super::ts_type::ts_type_ann_to_def;
+use super::ts_type::TsTypeDef;
+use super::Location;
+use super::ParamDef;
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct ClassConstructorDef {
+  pub js_doc: Option<String>,
+  pub accessibility: Option<swc_ecma_ast::Accessibility>,
+  pub name: String,
+  pub params: Vec<ParamDef>,
+  pub location: Location,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct ClassPropertyDef {
+  pub js_doc: Option<String>,
+  pub ts_type: Option<TsTypeDef>,
+  pub readonly: bool,
+  pub accessibility: Option<swc_ecma_ast::Accessibility>,
+  pub is_abstract: bool,
+  pub is_static: bool,
+  pub name: String,
+  pub location: Location,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct ClassMethodDef {
+  pub js_doc: Option<String>,
+  //   pub ts_type: Option<TsTypeDef>,
+  //   pub readonly: bool,
+  pub accessibility: Option<swc_ecma_ast::Accessibility>,
+  pub is_abstract: bool,
+  pub is_static: bool,
+  pub name: String,
+  pub kind: swc_ecma_ast::MethodKind,
+  pub function_def: FunctionDef,
+  pub location: Location,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct ClassDef {
+  // TODO: decorators, super_class, implements,
+  // type_params, super_type_params
+  pub is_abstract: bool,
+  pub constructors: Vec<ClassConstructorDef>,
+  pub properties: Vec<ClassPropertyDef>,
+  pub methods: Vec<ClassMethodDef>,
+}
+
+fn prop_name_to_string(
+  source_map: &SourceMap,
+  prop_name: &swc_ecma_ast::PropName,
+) -> String {
+  use swc_ecma_ast::PropName;
+  match prop_name {
+    PropName::Ident(ident) => ident.sym.to_string(),
+    PropName::Str(str_) => str_.value.to_string(),
+    PropName::Num(num) => num.value.to_string(),
+    PropName::Computed(comp_prop_name) => {
+      source_map.span_to_snippet(comp_prop_name.span).unwrap()
+    }
+  }
+}
+
+pub fn get_doc_for_class_decl(
+  doc_parser: &DocParser,
+  class_decl: &swc_ecma_ast::ClassDecl,
+) -> (String, ClassDef) {
+  let mut constructors = vec![];
+  let mut methods = vec![];
+  let mut properties = vec![];
+
+  for member in &class_decl.class.body {
+    use swc_ecma_ast::ClassMember::*;
+
+    match member {
+      Constructor(ctor) => {
+        let ctor_js_doc = doc_parser.js_doc_for_span(ctor.span());
+        let constructor_name =
+          prop_name_to_string(&doc_parser.source_map, &ctor.key);
+
+        let mut params = vec![];
+
+        for param in &ctor.params {
+          use swc_ecma_ast::Pat;
+          use swc_ecma_ast::PatOrTsParamProp::*;
+
+          let param_def = match param {
+            Pat(pat) => match pat {
+              Pat::Ident(ident) => {
+                let ts_type = ident
+                  .type_ann
+                  .as_ref()
+                  .map(|rt| ts_type_ann_to_def(&doc_parser.source_map, rt));
+
+                ParamDef {
+                  name: ident.sym.to_string(),
+                  ts_type,
+                }
+              }
+              _ => ParamDef {
+                name: "<TODO>".to_string(),
+                ts_type: None,
+              },
+            },
+            TsParamProp(_) => ParamDef {
+              name: "<TODO>".to_string(),
+              ts_type: None,
+            },
+          };
+          params.push(param_def);
+        }
+
+        let constructor_def = ClassConstructorDef {
+          js_doc: ctor_js_doc,
+          accessibility: ctor.accessibility,
+          name: constructor_name,
+          params,
+          location: doc_parser
+            .source_map
+            .lookup_char_pos(ctor.span.lo())
+            .into(),
+        };
+        constructors.push(constructor_def);
+      }
+      Method(class_method) => {
+        let method_js_doc = doc_parser.js_doc_for_span(class_method.span());
+        let method_name =
+          prop_name_to_string(&doc_parser.source_map, &class_method.key);
+        let fn_def =
+          function_to_function_def(doc_parser, &class_method.function);
+        let method_def = ClassMethodDef {
+          js_doc: method_js_doc,
+          accessibility: class_method.accessibility,
+          is_abstract: class_method.is_abstract,
+          is_static: class_method.is_static,
+          name: method_name,
+          kind: class_method.kind,
+          function_def: fn_def,
+          location: doc_parser
+            .source_map
+            .lookup_char_pos(class_method.span.lo())
+            .into(),
+        };
+        methods.push(method_def);
+      }
+      ClassProp(class_prop) => {
+        let prop_js_doc = doc_parser.js_doc_for_span(class_prop.span());
+
+        let ts_type = class_prop
+          .type_ann
+          .as_ref()
+          .map(|rt| ts_type_ann_to_def(&doc_parser.source_map, rt));
+
+        use swc_ecma_ast::Expr;
+        let prop_name = match &*class_prop.key {
+          Expr::Ident(ident) => ident.sym.to_string(),
+          _ => "<TODO>".to_string(),
+        };
+
+        let prop_def = ClassPropertyDef {
+          js_doc: prop_js_doc,
+          ts_type,
+          readonly: class_prop.readonly,
+          is_abstract: class_prop.is_abstract,
+          is_static: class_prop.is_static,
+          accessibility: class_prop.accessibility,
+          name: prop_name,
+          location: doc_parser
+            .source_map
+            .lookup_char_pos(class_prop.span.lo())
+            .into(),
+        };
+        properties.push(prop_def);
+      }
+      // TODO:
+      TsIndexSignature(_) => {}
+      PrivateMethod(_) => {}
+      PrivateProp(_) => {}
+    }
+  }
+
+  let class_name = class_decl.ident.sym.to_string();
+  let class_def = ClassDef {
+    is_abstract: class_decl.class.is_abstract,
+    constructors,
+    properties,
+    methods,
+  };
+
+  (class_name, class_def)
+}
diff --git a/cli/doc/enum.rs b/cli/doc/enum.rs
new file mode 100644
index 000000000..f71c15537
--- /dev/null
+++ b/cli/doc/enum.rs
@@ -0,0 +1,41 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use serde::Serialize;
+use swc_ecma_ast;
+
+use super::parser::DocParser;
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct EnumMemberDef {
+  pub name: String,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct EnumDef {
+  pub members: Vec<EnumMemberDef>,
+}
+
+pub fn get_doc_for_ts_enum_decl(
+  _doc_parser: &DocParser,
+  enum_decl: &swc_ecma_ast::TsEnumDecl,
+) -> (String, EnumDef) {
+  let enum_name = enum_decl.id.sym.to_string();
+  let mut members = vec![];
+
+  for enum_member in &enum_decl.members {
+    use swc_ecma_ast::TsEnumMemberId::*;
+
+    let member_name = match &enum_member.id {
+      Ident(ident) => ident.sym.to_string(),
+      Str(str_) => str_.value.to_string(),
+    };
+
+    let member_def = EnumMemberDef { name: member_name };
+    members.push(member_def);
+  }
+
+  let enum_def = EnumDef { members };
+
+  (enum_name, enum_def)
+}
diff --git a/cli/doc/function.rs b/cli/doc/function.rs
new file mode 100644
index 000000000..ec7f9bf38
--- /dev/null
+++ b/cli/doc/function.rs
@@ -0,0 +1,70 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use serde::Serialize;
+use swc_ecma_ast;
+
+use super::parser::DocParser;
+use super::ts_type::ts_type_ann_to_def;
+use super::ts_type::TsTypeDef;
+use super::ParamDef;
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct FunctionDef {
+  pub params: Vec<ParamDef>,
+  pub return_type: Option<TsTypeDef>,
+  pub is_async: bool,
+  pub is_generator: bool,
+  // TODO: type_params, decorators
+}
+
+pub fn function_to_function_def(
+  doc_parser: &DocParser,
+  function: &swc_ecma_ast::Function,
+) -> FunctionDef {
+  let mut params = vec![];
+
+  for param in &function.params {
+    use swc_ecma_ast::Pat;
+
+    let param_def = match param {
+      Pat::Ident(ident) => {
+        let ts_type = ident
+          .type_ann
+          .as_ref()
+          .map(|rt| ts_type_ann_to_def(&doc_parser.source_map, rt));
+
+        ParamDef {
+          name: ident.sym.to_string(),
+          ts_type,
+        }
+      }
+      _ => ParamDef {
+        name: "<TODO>".to_string(),
+        ts_type: None,
+      },
+    };
+
+    params.push(param_def);
+  }
+
+  let maybe_return_type = function
+    .return_type
+    .as_ref()
+    .map(|rt| ts_type_ann_to_def(&doc_parser.source_map, rt));
+
+  FunctionDef {
+    params,
+    return_type: maybe_return_type,
+    is_async: function.is_async,
+    is_generator: function.is_generator,
+  }
+}
+
+pub fn get_doc_for_fn_decl(
+  doc_parser: &DocParser,
+  fn_decl: &swc_ecma_ast::FnDecl,
+) -> (String, FunctionDef) {
+  let name = fn_decl.ident.sym.to_string();
+  let fn_def = function_to_function_def(doc_parser, &fn_decl.function);
+  (name, fn_def)
+}
diff --git a/cli/doc/interface.rs b/cli/doc/interface.rs
new file mode 100644
index 000000000..b7e123773
--- /dev/null
+++ b/cli/doc/interface.rs
@@ -0,0 +1,243 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use serde::Serialize;
+use swc_ecma_ast;
+
+use super::parser::DocParser;
+use super::ts_type::ts_type_ann_to_def;
+use super::ts_type::TsTypeDef;
+use super::Location;
+use super::ParamDef;
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct InterfaceMethodDef {
+  // TODO: type_params
+  pub name: String,
+  pub location: Location,
+  pub js_doc: Option<String>,
+  pub params: Vec<ParamDef>,
+  pub return_type: Option<TsTypeDef>,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct InterfacePropertyDef {
+  // TODO: type_params
+  pub name: String,
+  pub location: Location,
+  pub js_doc: Option<String>,
+  pub params: Vec<ParamDef>,
+  pub computed: bool,
+  pub optional: bool,
+  pub ts_type: Option<TsTypeDef>,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct InterfaceCallSignatureDef {
+  // TODO: type_params
+  pub location: Location,
+  pub js_doc: Option<String>,
+  pub params: Vec<ParamDef>,
+  pub ts_type: Option<TsTypeDef>,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct InterfaceDef {
+  // TODO: extends, type params
+  pub methods: Vec<InterfaceMethodDef>,
+  pub properties: Vec<InterfacePropertyDef>,
+  pub call_signatures: Vec<InterfaceCallSignatureDef>,
+}
+
+fn expr_to_name(expr: &swc_ecma_ast::Expr) -> String {
+  use swc_ecma_ast::Expr::*;
+  use swc_ecma_ast::ExprOrSuper::*;
+
+  match expr {
+    Ident(ident) => ident.sym.to_string(),
+    Member(member_expr) => {
+      let left = match &member_expr.obj {
+        Super(_) => "TODO".to_string(),
+        Expr(boxed_expr) => expr_to_name(&*boxed_expr),
+      };
+      let right = expr_to_name(&*member_expr.prop);
+      format!("[{}.{}]", left, right)
+    }
+    _ => "<TODO>".to_string(),
+  }
+}
+
+pub fn get_doc_for_ts_interface_decl(
+  doc_parser: &DocParser,
+  interface_decl: &swc_ecma_ast::TsInterfaceDecl,
+) -> (String, InterfaceDef) {
+  let interface_name = interface_decl.id.sym.to_string();
+
+  let mut methods = vec![];
+  let mut properties = vec![];
+  let mut call_signatures = vec![];
+
+  for type_element in &interface_decl.body.body {
+    use swc_ecma_ast::TsTypeElement::*;
+
+    match &type_element {
+      TsMethodSignature(ts_method_sig) => {
+        let method_js_doc = doc_parser.js_doc_for_span(ts_method_sig.span);
+
+        let mut params = vec![];
+
+        for param in &ts_method_sig.params {
+          use swc_ecma_ast::TsFnParam::*;
+
+          let param_def = match param {
+            Ident(ident) => {
+              let ts_type = ident
+                .type_ann
+                .as_ref()
+                .map(|rt| ts_type_ann_to_def(&doc_parser.source_map, rt));
+
+              ParamDef {
+                name: ident.sym.to_string(),
+                ts_type,
+              }
+            }
+            _ => ParamDef {
+              name: "<TODO>".to_string(),
+              ts_type: None,
+            },
+          };
+
+          params.push(param_def);
+        }
+
+        let name = expr_to_name(&*ts_method_sig.key);
+
+        let maybe_return_type = ts_method_sig
+          .type_ann
+          .as_ref()
+          .map(|rt| ts_type_ann_to_def(&doc_parser.source_map, rt));
+
+        let method_def = InterfaceMethodDef {
+          name,
+          js_doc: method_js_doc,
+          location: doc_parser
+            .source_map
+            .lookup_char_pos(ts_method_sig.span.lo())
+            .into(),
+          params,
+          return_type: maybe_return_type,
+        };
+        methods.push(method_def);
+      }
+      TsPropertySignature(ts_prop_sig) => {
+        let prop_js_doc = doc_parser.js_doc_for_span(ts_prop_sig.span);
+        let name = match &*ts_prop_sig.key {
+          swc_ecma_ast::Expr::Ident(ident) => ident.sym.to_string(),
+          _ => "TODO".to_string(),
+        };
+
+        let mut params = vec![];
+
+        for param in &ts_prop_sig.params {
+          use swc_ecma_ast::TsFnParam::*;
+
+          let param_def = match param {
+            Ident(ident) => {
+              let ts_type = ident
+                .type_ann
+                .as_ref()
+                .map(|rt| ts_type_ann_to_def(&doc_parser.source_map, rt));
+
+              ParamDef {
+                name: ident.sym.to_string(),
+                ts_type,
+              }
+            }
+            _ => ParamDef {
+              name: "<TODO>".to_string(),
+              ts_type: None,
+            },
+          };
+
+          params.push(param_def);
+        }
+
+        let ts_type = ts_prop_sig
+          .type_ann
+          .as_ref()
+          .map(|rt| ts_type_ann_to_def(&doc_parser.source_map, rt));
+
+        let prop_def = InterfacePropertyDef {
+          name,
+          js_doc: prop_js_doc,
+          location: doc_parser
+            .source_map
+            .lookup_char_pos(ts_prop_sig.span.lo())
+            .into(),
+          params,
+          ts_type,
+          computed: ts_prop_sig.computed,
+          optional: ts_prop_sig.optional,
+        };
+        properties.push(prop_def);
+      }
+      TsCallSignatureDecl(ts_call_sig) => {
+        let call_sig_js_doc = doc_parser.js_doc_for_span(ts_call_sig.span);
+
+        let mut params = vec![];
+        for param in &ts_call_sig.params {
+          use swc_ecma_ast::TsFnParam::*;
+
+          let param_def = match param {
+            Ident(ident) => {
+              let ts_type = ident
+                .type_ann
+                .as_ref()
+                .map(|rt| ts_type_ann_to_def(&doc_parser.source_map, rt));
+
+              ParamDef {
+                name: ident.sym.to_string(),
+                ts_type,
+              }
+            }
+            _ => ParamDef {
+              name: "<TODO>".to_string(),
+              ts_type: None,
+            },
+          };
+
+          params.push(param_def);
+        }
+
+        let ts_type = ts_call_sig
+          .type_ann
+          .as_ref()
+          .map(|rt| ts_type_ann_to_def(&doc_parser.source_map, rt));
+
+        let call_sig_def = InterfaceCallSignatureDef {
+          js_doc: call_sig_js_doc,
+          location: doc_parser
+            .source_map
+            .lookup_char_pos(ts_call_sig.span.lo())
+            .into(),
+          params,
+          ts_type,
+        };
+        call_signatures.push(call_sig_def);
+      }
+      // TODO:
+      TsConstructSignatureDecl(_) => {}
+      TsIndexSignature(_) => {}
+    }
+  }
+
+  let interface_def = InterfaceDef {
+    methods,
+    properties,
+    call_signatures,
+  };
+
+  (interface_name, interface_def)
+}
diff --git a/cli/doc/mod.rs b/cli/doc/mod.rs
new file mode 100644
index 000000000..4926dccd7
--- /dev/null
+++ b/cli/doc/mod.rs
@@ -0,0 +1,63 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+pub mod class;
+pub mod r#enum;
+pub mod function;
+pub mod interface;
+pub mod module;
+pub mod namespace;
+mod node;
+pub mod parser;
+pub mod printer;
+pub mod ts_type;
+pub mod type_alias;
+pub mod variable;
+
+pub use node::DocNode;
+pub use node::DocNodeKind;
+pub use node::Location;
+pub use node::ParamDef;
+pub use parser::DocParser;
+
+#[cfg(test)]
+mod tests;
+
+pub fn find_node_by_name_recursively(
+  doc_nodes: Vec<DocNode>,
+  name: String,
+) -> Option<DocNode> {
+  let mut parts = name.splitn(2, '.');
+  let name = parts.next();
+  let leftover = parts.next();
+  name?;
+  let node = find_node_by_name(doc_nodes, name.unwrap().to_string());
+  match node {
+    Some(node) => match node.kind {
+      DocNodeKind::Namespace => {
+        if let Some(leftover) = leftover {
+          find_node_by_name_recursively(
+            node.namespace_def.unwrap().elements,
+            leftover.to_string(),
+          )
+        } else {
+          Some(node)
+        }
+      }
+      _ => {
+        if leftover.is_none() {
+          Some(node)
+        } else {
+          None
+        }
+      }
+    },
+    _ => None,
+  }
+}
+
+fn find_node_by_name(doc_nodes: Vec<DocNode>, name: String) -> Option<DocNode> {
+  let node = doc_nodes.iter().find(|node| node.name == name);
+  match node {
+    Some(node) => Some(node.clone()),
+    None => None,
+  }
+}
diff --git a/cli/doc/module.rs b/cli/doc/module.rs
new file mode 100644
index 000000000..e6c97771a
--- /dev/null
+++ b/cli/doc/module.rs
@@ -0,0 +1,189 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use swc_common;
+use swc_common::Spanned;
+use swc_ecma_ast;
+
+use super::parser::DocParser;
+use super::DocNode;
+use super::DocNodeKind;
+
+pub fn get_doc_node_for_export_decl(
+  doc_parser: &DocParser,
+  export_decl: &swc_ecma_ast::ExportDecl,
+) -> DocNode {
+  let export_span = export_decl.span();
+  use swc_ecma_ast::Decl;
+
+  let js_doc = doc_parser.js_doc_for_span(export_span);
+  let location = doc_parser
+    .source_map
+    .lookup_char_pos(export_span.lo())
+    .into();
+
+  match &export_decl.decl {
+    Decl::Class(class_decl) => {
+      let (name, class_def) =
+        super::class::get_doc_for_class_decl(doc_parser, class_decl);
+      DocNode {
+        kind: DocNodeKind::Class,
+        name,
+        location,
+        js_doc,
+        class_def: Some(class_def),
+        function_def: None,
+        variable_def: None,
+        enum_def: None,
+        type_alias_def: None,
+        namespace_def: None,
+        interface_def: None,
+      }
+    }
+    Decl::Fn(fn_decl) => {
+      let (name, function_def) =
+        super::function::get_doc_for_fn_decl(doc_parser, fn_decl);
+      DocNode {
+        kind: DocNodeKind::Function,
+        name,
+        location,
+        js_doc,
+        function_def: Some(function_def),
+        class_def: None,
+        variable_def: None,
+        enum_def: None,
+        type_alias_def: None,
+        namespace_def: None,
+        interface_def: None,
+      }
+    }
+    Decl::Var(var_decl) => {
+      let (name, var_def) =
+        super::variable::get_doc_for_var_decl(doc_parser, var_decl);
+      DocNode {
+        kind: DocNodeKind::Variable,
+        name,
+        location,
+        js_doc,
+        variable_def: Some(var_def),
+        function_def: None,
+        class_def: None,
+        enum_def: None,
+        type_alias_def: None,
+        namespace_def: None,
+        interface_def: None,
+      }
+    }
+    Decl::TsInterface(ts_interface_decl) => {
+      let (name, interface_def) =
+        super::interface::get_doc_for_ts_interface_decl(
+          doc_parser,
+          ts_interface_decl,
+        );
+      DocNode {
+        kind: DocNodeKind::Interface,
+        name,
+        location,
+        js_doc,
+        interface_def: Some(interface_def),
+        variable_def: None,
+        function_def: None,
+        class_def: None,
+        enum_def: None,
+        type_alias_def: None,
+        namespace_def: None,
+      }
+    }
+    Decl::TsTypeAlias(ts_type_alias) => {
+      let (name, type_alias_def) =
+        super::type_alias::get_doc_for_ts_type_alias_decl(
+          doc_parser,
+          ts_type_alias,
+        );
+      DocNode {
+        kind: DocNodeKind::TypeAlias,
+        name,
+        location,
+        js_doc,
+        type_alias_def: Some(type_alias_def),
+        interface_def: None,
+        variable_def: None,
+        function_def: None,
+        class_def: None,
+        enum_def: None,
+        namespace_def: None,
+      }
+    }
+    Decl::TsEnum(ts_enum) => {
+      let (name, enum_def) =
+        super::r#enum::get_doc_for_ts_enum_decl(doc_parser, ts_enum);
+      DocNode {
+        kind: DocNodeKind::Enum,
+        name,
+        location,
+        js_doc,
+        enum_def: Some(enum_def),
+        type_alias_def: None,
+        interface_def: None,
+        variable_def: None,
+        function_def: None,
+        class_def: None,
+        namespace_def: None,
+      }
+    }
+    Decl::TsModule(ts_module) => {
+      let (name, namespace_def) =
+        super::namespace::get_doc_for_ts_module(doc_parser, ts_module);
+      DocNode {
+        kind: DocNodeKind::Namespace,
+        name,
+        location,
+        js_doc,
+        namespace_def: Some(namespace_def),
+        enum_def: None,
+        type_alias_def: None,
+        interface_def: None,
+        variable_def: None,
+        function_def: None,
+        class_def: None,
+      }
+    }
+  }
+}
+
+#[allow(unused)]
+pub fn get_doc_nodes_for_named_export(
+  doc_parser: &DocParser,
+  named_export: &swc_ecma_ast::NamedExport,
+) -> Vec<DocNode> {
+  let file_name = named_export.src.as_ref().expect("").value.to_string();
+  // TODO: resolve specifier
+  let source_code =
+    std::fs::read_to_string(&file_name).expect("Failed to read file");
+  let doc_nodes = doc_parser
+    .parse(file_name, source_code)
+    .expect("Failed to print docs");
+  let reexports: Vec<String> = named_export
+    .specifiers
+    .iter()
+    .map(|export_specifier| {
+      use swc_ecma_ast::ExportSpecifier::*;
+
+      match export_specifier {
+        Named(named_export_specifier) => {
+          Some(named_export_specifier.orig.sym.to_string())
+        }
+        // TODO:
+        Namespace(_) => None,
+        Default(_) => None,
+      }
+    })
+    .filter(|s| s.is_some())
+    .map(|s| s.unwrap())
+    .collect();
+
+  let reexports_docs: Vec<DocNode> = doc_nodes
+    .into_iter()
+    .filter(|doc_node| reexports.contains(&doc_node.name))
+    .collect();
+
+  reexports_docs
+}
diff --git a/cli/doc/namespace.rs b/cli/doc/namespace.rs
new file mode 100644
index 000000000..ed6aac2f3
--- /dev/null
+++ b/cli/doc/namespace.rs
@@ -0,0 +1,81 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use serde::Serialize;
+use swc_ecma_ast;
+
+use super::parser::DocParser;
+use super::DocNode;
+use super::DocNodeKind;
+
+#[derive(Debug, Serialize, Clone)]
+pub struct NamespaceDef {
+  pub elements: Vec<DocNode>,
+}
+
+pub fn get_doc_for_ts_namespace_decl(
+  doc_parser: &DocParser,
+  ts_namespace_decl: &swc_ecma_ast::TsNamespaceDecl,
+) -> DocNode {
+  let js_doc = doc_parser.js_doc_for_span(ts_namespace_decl.span);
+  let location = doc_parser
+    .source_map
+    .lookup_char_pos(ts_namespace_decl.span.lo())
+    .into();
+  let namespace_name = ts_namespace_decl.id.sym.to_string();
+
+  use swc_ecma_ast::TsNamespaceBody::*;
+
+  let elements = match &*ts_namespace_decl.body {
+    TsModuleBlock(ts_module_block) => {
+      doc_parser.get_doc_nodes_for_module_body(ts_module_block.body.clone())
+    }
+    TsNamespaceDecl(ts_namespace_decl) => {
+      vec![get_doc_for_ts_namespace_decl(doc_parser, ts_namespace_decl)]
+    }
+  };
+
+  let ns_def = NamespaceDef { elements };
+
+  DocNode {
+    kind: DocNodeKind::Namespace,
+    name: namespace_name,
+    location,
+    js_doc,
+    namespace_def: Some(ns_def),
+    function_def: None,
+    variable_def: None,
+    enum_def: None,
+    class_def: None,
+    type_alias_def: None,
+    interface_def: None,
+  }
+}
+
+pub fn get_doc_for_ts_module(
+  doc_parser: &DocParser,
+  ts_module_decl: &swc_ecma_ast::TsModuleDecl,
+) -> (String, NamespaceDef) {
+  use swc_ecma_ast::TsModuleName;
+  let namespace_name = match &ts_module_decl.id {
+    TsModuleName::Ident(ident) => ident.sym.to_string(),
+    TsModuleName::Str(str_) => str_.value.to_string(),
+  };
+
+  let elements = if let Some(body) = &ts_module_decl.body {
+    use swc_ecma_ast::TsNamespaceBody::*;
+
+    match &body {
+      TsModuleBlock(ts_module_block) => {
+        doc_parser.get_doc_nodes_for_module_body(ts_module_block.body.clone())
+      }
+      TsNamespaceDecl(ts_namespace_decl) => {
+        vec![get_doc_for_ts_namespace_decl(doc_parser, ts_namespace_decl)]
+      }
+    }
+  } else {
+    vec![]
+  };
+
+  let ns_def = NamespaceDef { elements };
+
+  (namespace_name, ns_def)
+}
diff --git a/cli/doc/node.rs b/cli/doc/node.rs
new file mode 100644
index 000000000..da4b81c11
--- /dev/null
+++ b/cli/doc/node.rs
@@ -0,0 +1,77 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use serde::Serialize;
+use swc_common;
+
+#[derive(Debug, PartialEq, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub enum DocNodeKind {
+  Function,
+  Variable,
+  Class,
+  Enum,
+  Interface,
+  TypeAlias,
+  Namespace,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct ParamDef {
+  pub name: String,
+  pub ts_type: Option<super::ts_type::TsTypeDef>,
+}
+
+#[derive(Debug, Serialize, Clone)]
+pub struct Location {
+  pub filename: String,
+  pub line: usize,
+  pub col: usize,
+}
+
+impl Into<Location> for swc_common::Loc {
+  fn into(self) -> Location {
+    use swc_common::FileName::*;
+
+    let filename = match &self.file.name {
+      Real(path_buf) => path_buf.to_string_lossy().to_string(),
+      Custom(str_) => str_.to_string(),
+      _ => panic!("invalid filename"),
+    };
+
+    Location {
+      filename,
+      line: self.line,
+      col: self.col_display,
+    }
+  }
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct DocNode {
+  pub kind: DocNodeKind,
+  pub name: String,
+  pub location: Location,
+  pub js_doc: Option<String>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub function_def: Option<super::function::FunctionDef>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub variable_def: Option<super::variable::VariableDef>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub enum_def: Option<super::r#enum::EnumDef>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub class_def: Option<super::class::ClassDef>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub type_alias_def: Option<super::type_alias::TypeAliasDef>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub namespace_def: Option<super::namespace::NamespaceDef>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub interface_def: Option<super::interface::InterfaceDef>,
+}
diff --git a/cli/doc/parser.rs b/cli/doc/parser.rs
new file mode 100644
index 000000000..bd3a64806
--- /dev/null
+++ b/cli/doc/parser.rs
@@ -0,0 +1,189 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use regex::Regex;
+use std::sync::Arc;
+use std::sync::RwLock;
+use swc_common;
+use swc_common::comments::CommentKind;
+use swc_common::comments::Comments;
+use swc_common::errors::Diagnostic;
+use swc_common::errors::DiagnosticBuilder;
+use swc_common::errors::Emitter;
+use swc_common::errors::Handler;
+use swc_common::errors::HandlerFlags;
+use swc_common::FileName;
+use swc_common::Globals;
+use swc_common::SourceMap;
+use swc_common::Span;
+use swc_ecma_parser::lexer::Lexer;
+use swc_ecma_parser::JscTarget;
+use swc_ecma_parser::Parser;
+use swc_ecma_parser::Session;
+use swc_ecma_parser::SourceFileInput;
+use swc_ecma_parser::Syntax;
+use swc_ecma_parser::TsConfig;
+
+use super::DocNode;
+
+pub type SwcDiagnostics = Vec<Diagnostic>;
+
+#[derive(Clone, Default)]
+pub struct BufferedError(Arc<RwLock<SwcDiagnostics>>);
+
+impl Emitter for BufferedError {
+  fn emit(&mut self, db: &DiagnosticBuilder) {
+    self.0.write().unwrap().push((**db).clone());
+  }
+}
+
+impl From<BufferedError> for Vec<Diagnostic> {
+  fn from(buf: BufferedError) -> Self {
+    let s = buf.0.read().unwrap();
+    s.clone()
+  }
+}
+
+pub struct DocParser {
+  pub buffered_error: BufferedError,
+  pub source_map: Arc<SourceMap>,
+  pub handler: Handler,
+  pub comments: Comments,
+  pub globals: Globals,
+}
+
+impl DocParser {
+  pub fn default() -> Self {
+    let buffered_error = BufferedError::default();
+
+    let handler = Handler::with_emitter_and_flags(
+      Box::new(buffered_error.clone()),
+      HandlerFlags {
+        dont_buffer_diagnostics: true,
+        can_emit_warnings: true,
+        ..Default::default()
+      },
+    );
+
+    DocParser {
+      buffered_error,
+      source_map: Arc::new(SourceMap::default()),
+      handler,
+      comments: Comments::default(),
+      globals: Globals::new(),
+    }
+  }
+
+  pub fn parse(
+    &self,
+    file_name: String,
+    source_code: String,
+  ) -> Result<Vec<DocNode>, SwcDiagnostics> {
+    swc_common::GLOBALS.set(&self.globals, || {
+      let swc_source_file = self
+        .source_map
+        .new_source_file(FileName::Custom(file_name), source_code);
+
+      let buffered_err = self.buffered_error.clone();
+      let session = Session {
+        handler: &self.handler,
+      };
+
+      let mut ts_config = TsConfig::default();
+      ts_config.dynamic_import = true;
+      let syntax = Syntax::Typescript(ts_config);
+
+      let lexer = Lexer::new(
+        session,
+        syntax,
+        JscTarget::Es2019,
+        SourceFileInput::from(&*swc_source_file),
+        Some(&self.comments),
+      );
+
+      let mut parser = Parser::new_from(session, lexer);
+
+      let module =
+        parser
+          .parse_module()
+          .map_err(move |mut err: DiagnosticBuilder| {
+            err.cancel();
+            SwcDiagnostics::from(buffered_err)
+          })?;
+
+      let doc_entries = self.get_doc_nodes_for_module_body(module.body);
+      Ok(doc_entries)
+    })
+  }
+
+  pub fn get_doc_nodes_for_module_decl(
+    &self,
+    module_decl: &swc_ecma_ast::ModuleDecl,
+  ) -> Vec<DocNode> {
+    use swc_ecma_ast::ModuleDecl;
+
+    match module_decl {
+      ModuleDecl::ExportDecl(export_decl) => {
+        vec![super::module::get_doc_node_for_export_decl(
+          self,
+          export_decl,
+        )]
+      }
+      ModuleDecl::ExportNamed(_named_export) => {
+        vec![]
+        // TODO(bartlomieju):
+        // super::module::get_doc_nodes_for_named_export(self, named_export)
+      }
+      ModuleDecl::ExportDefaultDecl(_) => vec![],
+      ModuleDecl::ExportDefaultExpr(_) => vec![],
+      ModuleDecl::ExportAll(_) => vec![],
+      ModuleDecl::TsExportAssignment(_) => vec![],
+      ModuleDecl::TsNamespaceExport(_) => vec![],
+      _ => vec![],
+    }
+  }
+
+  pub fn get_doc_nodes_for_module_body(
+    &self,
+    module_body: Vec<swc_ecma_ast::ModuleItem>,
+  ) -> Vec<DocNode> {
+    let mut doc_entries: Vec<DocNode> = vec![];
+    for node in module_body.iter() {
+      if let swc_ecma_ast::ModuleItem::ModuleDecl(module_decl) = node {
+        doc_entries.extend(self.get_doc_nodes_for_module_decl(module_decl));
+      }
+    }
+    doc_entries
+  }
+
+  pub fn js_doc_for_span(&self, span: Span) -> Option<String> {
+    let comments = self.comments.take_leading_comments(span.lo())?;
+    let js_doc_comment = comments.iter().find(|comment| {
+      comment.kind == CommentKind::Block && comment.text.starts_with('*')
+    })?;
+
+    let mut margin_pat = String::from("");
+    if let Some(margin) = self.source_map.span_to_margin(span) {
+      for _ in 0..margin {
+        margin_pat.push(' ');
+      }
+    }
+
+    let js_doc_re = Regex::new(r#" ?\* ?"#).unwrap();
+    let txt = js_doc_comment
+      .text
+      .split('\n')
+      .map(|line| js_doc_re.replace(line, "").to_string())
+      .map(|line| {
+        if line.starts_with(&margin_pat) {
+          line[margin_pat.len()..].to_string()
+        } else {
+          line
+        }
+      })
+      .collect::<Vec<String>>()
+      .join("\n");
+
+    let txt = txt.trim_start().trim_end().to_string();
+
+    Some(txt)
+  }
+}
diff --git a/cli/doc/printer.rs b/cli/doc/printer.rs
new file mode 100644
index 000000000..a58f2fcdc
--- /dev/null
+++ b/cli/doc/printer.rs
@@ -0,0 +1,432 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+// TODO(ry) This module builds up output by appending to a string. Instead it
+// should either use a formatting trait
+// https://doc.rust-lang.org/std/fmt/index.html#formatting-traits
+// Or perhaps implement a Serializer for serde
+// https://docs.serde.rs/serde/ser/trait.Serializer.html
+
+// TODO(ry) The methods in this module take ownership of the DocNodes, this is
+// unnecessary and can result in unnecessary copying. Instead they should take
+// references.
+
+use crate::doc;
+use crate::doc::ts_type::TsTypeDefKind;
+use crate::doc::DocNodeKind;
+
+pub fn format(doc_nodes: Vec<doc::DocNode>) -> String {
+  format_(doc_nodes, 0)
+}
+
+pub fn format_details(node: doc::DocNode) -> String {
+  let mut details = String::new();
+
+  details.push_str(&format!(
+    "Defined in {}:{}:{}.\n",
+    node.location.filename, node.location.line, node.location.col
+  ));
+
+  details.push_str(&format_signature(&node, 0));
+
+  let js_doc = node.js_doc.clone();
+  if let Some(js_doc) = js_doc {
+    details.push_str(&format_jsdoc(js_doc, false, 1));
+  }
+  details.push_str("\n");
+
+  let maybe_extra = match node.kind {
+    DocNodeKind::Class => Some(format_class_details(node)),
+    DocNodeKind::Namespace => Some(format_namespace_details(node)),
+    _ => None,
+  };
+
+  if let Some(extra) = maybe_extra {
+    details.push_str(&extra);
+  }
+
+  details
+}
+
+fn kind_order(kind: &doc::DocNodeKind) -> i64 {
+  match kind {
+    DocNodeKind::Function => 0,
+    DocNodeKind::Variable => 1,
+    DocNodeKind::Class => 2,
+    DocNodeKind::Enum => 3,
+    DocNodeKind::Interface => 4,
+    DocNodeKind::TypeAlias => 5,
+    DocNodeKind::Namespace => 6,
+  }
+}
+
+fn format_signature(node: &doc::DocNode, indent: i64) -> String {
+  match node.kind {
+    DocNodeKind::Function => format_function_signature(&node, indent),
+    DocNodeKind::Variable => format_variable_signature(&node, indent),
+    DocNodeKind::Class => format_class_signature(&node, indent),
+    DocNodeKind::Enum => format_enum_signature(&node, indent),
+    DocNodeKind::Interface => format_interface_signature(&node, indent),
+    DocNodeKind::TypeAlias => format_type_alias_signature(&node, indent),
+    DocNodeKind::Namespace => format_namespace_signature(&node, indent),
+  }
+}
+
+fn format_(doc_nodes: Vec<doc::DocNode>, indent: i64) -> String {
+  let mut sorted = doc_nodes;
+  sorted.sort_unstable_by(|a, b| {
+    let kind_cmp = kind_order(&a.kind).cmp(&kind_order(&b.kind));
+    if kind_cmp == core::cmp::Ordering::Equal {
+      a.name.cmp(&b.name)
+    } else {
+      kind_cmp
+    }
+  });
+
+  let mut output = String::new();
+
+  for node in sorted {
+    output.push_str(&format_signature(&node, indent));
+    if node.js_doc.is_some() {
+      output.push_str(&format_jsdoc(
+        node.js_doc.as_ref().unwrap().to_string(),
+        true,
+        indent,
+      ));
+    }
+    output.push_str("\n");
+    if DocNodeKind::Namespace == node.kind {
+      output.push_str(&format_(
+        node.namespace_def.as_ref().unwrap().elements.clone(),
+        indent + 1,
+      ));
+      output.push_str("\n");
+    };
+  }
+
+  output
+}
+
+fn render_params(params: Vec<doc::ParamDef>) -> String {
+  let mut rendered = String::from("");
+  if !params.is_empty() {
+    for param in params {
+      rendered += param.name.as_str();
+      if param.ts_type.is_some() {
+        rendered += ": ";
+        rendered += render_ts_type(param.ts_type.unwrap()).as_str();
+      }
+      rendered += ", ";
+    }
+    rendered.truncate(rendered.len() - 2);
+  }
+  rendered
+}
+
+fn render_ts_type(ts_type: doc::ts_type::TsTypeDef) -> String {
+  let kind = ts_type.kind.unwrap();
+  match kind {
+    TsTypeDefKind::Array => {
+      format!("{}[]", render_ts_type(*ts_type.array.unwrap()))
+    }
+    TsTypeDefKind::Conditional => {
+      let conditional = ts_type.conditional_type.unwrap();
+      format!(
+        "{} extends {} ? {} : {}",
+        render_ts_type(*conditional.check_type),
+        render_ts_type(*conditional.extends_type),
+        render_ts_type(*conditional.true_type),
+        render_ts_type(*conditional.false_type)
+      )
+    }
+    TsTypeDefKind::FnOrConstructor => {
+      let fn_or_constructor = ts_type.fn_or_constructor.unwrap();
+      format!(
+        "{}({}) => {}",
+        if fn_or_constructor.constructor {
+          "new "
+        } else {
+          ""
+        },
+        render_params(fn_or_constructor.params),
+        render_ts_type(fn_or_constructor.ts_type),
+      )
+    }
+    TsTypeDefKind::IndexedAccess => {
+      let indexed_access = ts_type.indexed_access.unwrap();
+      format!(
+        "{}[{}]",
+        render_ts_type(*indexed_access.obj_type),
+        render_ts_type(*indexed_access.index_type)
+      )
+    }
+    TsTypeDefKind::Intersection => {
+      let intersection = ts_type.intersection.unwrap();
+      let mut output = "".to_string();
+      if !intersection.is_empty() {
+        for ts_type in intersection {
+          output += render_ts_type(ts_type).as_str();
+          output += " & "
+        }
+        output.truncate(output.len() - 3);
+      }
+      output
+    }
+    TsTypeDefKind::Keyword => ts_type.keyword.unwrap(),
+    TsTypeDefKind::Literal => {
+      let literal = ts_type.literal.unwrap();
+      match literal.kind {
+        doc::ts_type::LiteralDefKind::Boolean => {
+          format!("{}", literal.boolean.unwrap())
+        }
+        doc::ts_type::LiteralDefKind::String => {
+          "\"".to_string() + literal.string.unwrap().as_str() + "\""
+        }
+        doc::ts_type::LiteralDefKind::Number => {
+          format!("{}", literal.number.unwrap())
+        }
+      }
+    }
+    TsTypeDefKind::Optional => "_optional_".to_string(),
+    TsTypeDefKind::Parenthesized => {
+      format!("({})", render_ts_type(*ts_type.parenthesized.unwrap()))
+    }
+    TsTypeDefKind::Rest => {
+      format!("...{}", render_ts_type(*ts_type.rest.unwrap()))
+    }
+    TsTypeDefKind::This => "this".to_string(),
+    TsTypeDefKind::Tuple => {
+      let tuple = ts_type.tuple.unwrap();
+      let mut output = "".to_string();
+      if !tuple.is_empty() {
+        for ts_type in tuple {
+          output += render_ts_type(ts_type).as_str();
+          output += ", "
+        }
+        output.truncate(output.len() - 2);
+      }
+      output
+    }
+    TsTypeDefKind::TypeLiteral => {
+      let mut output = "".to_string();
+      let type_literal = ts_type.type_literal.unwrap();
+      for node in type_literal.call_signatures {
+        output += format!(
+          "({}): {}, ",
+          render_params(node.params),
+          render_ts_type(node.ts_type.unwrap())
+        )
+        .as_str()
+      }
+      for node in type_literal.methods {
+        output += format!(
+          "{}({}): {}, ",
+          node.name,
+          render_params(node.params),
+          render_ts_type(node.return_type.unwrap())
+        )
+        .as_str()
+      }
+      for node in type_literal.properties {
+        output +=
+          format!("{}: {}, ", node.name, render_ts_type(node.ts_type.unwrap()))
+            .as_str()
+      }
+      if !output.is_empty() {
+        output.truncate(output.len() - 2);
+      }
+      "{ ".to_string() + output.as_str() + " }"
+    }
+    TsTypeDefKind::TypeOperator => {
+      let operator = ts_type.type_operator.unwrap();
+      format!("{} {}", operator.operator, render_ts_type(operator.ts_type))
+    }
+    TsTypeDefKind::TypeQuery => {
+      format!("typeof {}", ts_type.type_query.unwrap())
+    }
+    TsTypeDefKind::TypeRef => {
+      let type_ref = ts_type.type_ref.unwrap();
+      let mut final_output = type_ref.type_name;
+      if type_ref.type_params.is_some() {
+        let mut output = "".to_string();
+        let type_params = type_ref.type_params.unwrap();
+        if !type_params.is_empty() {
+          for ts_type in type_params {
+            output += render_ts_type(ts_type).as_str();
+            output += ", "
+          }
+          output.truncate(output.len() - 2);
+        }
+        final_output += format!("<{}>", output).as_str();
+      }
+      final_output
+    }
+    TsTypeDefKind::Union => {
+      let union = ts_type.union.unwrap();
+      let mut output = "".to_string();
+      if !union.is_empty() {
+        for ts_type in union {
+          output += render_ts_type(ts_type).as_str();
+          output += " | "
+        }
+        output.truncate(output.len() - 3);
+      }
+      output
+    }
+  }
+}
+
+fn format_indent(indent: i64) -> String {
+  let mut indent_str = String::new();
+  for _ in 0..indent {
+    indent_str.push_str(" ");
+  }
+  indent_str
+}
+
+// TODO: this should use some sort of markdown to console parser.
+fn format_jsdoc(jsdoc: String, truncated: bool, indent: i64) -> String {
+  let mut lines = jsdoc.split("\n\n").map(|line| line.replace("\n", " "));
+
+  let mut js_doc = String::new();
+
+  if truncated {
+    let first_line = lines.next().unwrap_or_else(|| "".to_string());
+    js_doc.push_str(&format_indent(indent + 1));
+    js_doc.push_str(&format!("{}\n", first_line));
+  } else {
+    for line in lines {
+      js_doc.push_str(&format_indent(indent + 1));
+      js_doc.push_str(&format!("{}\n", line));
+    }
+  }
+  js_doc
+}
+
+fn format_class_details(node: doc::DocNode) -> String {
+  let mut details = String::new();
+
+  let class_def = node.class_def.unwrap();
+  for node in class_def.constructors {
+    details.push_str(&format!(
+      "constructor {}({})\n",
+      node.name,
+      render_params(node.params),
+    ));
+  }
+  for node in class_def.properties.iter().filter(|node| {
+    node
+      .accessibility
+      .unwrap_or(swc_ecma_ast::Accessibility::Public)
+      != swc_ecma_ast::Accessibility::Private
+  }) {
+    details.push_str(&format!(
+      "{} {}: {}\n",
+      match node
+        .accessibility
+        .unwrap_or(swc_ecma_ast::Accessibility::Public)
+      {
+        swc_ecma_ast::Accessibility::Protected => "protected".to_string(),
+        swc_ecma_ast::Accessibility::Public => "public".to_string(),
+        _ => "".to_string(),
+      },
+      node.name,
+      render_ts_type(node.ts_type.clone().unwrap())
+    ));
+  }
+  for node in class_def.methods.iter().filter(|node| {
+    node
+      .accessibility
+      .unwrap_or(swc_ecma_ast::Accessibility::Public)
+      != swc_ecma_ast::Accessibility::Private
+  }) {
+    let function_def = node.function_def.clone();
+    details.push_str(&format!(
+      "{} {}{}({}): {}\n",
+      match node
+        .accessibility
+        .unwrap_or(swc_ecma_ast::Accessibility::Public)
+      {
+        swc_ecma_ast::Accessibility::Protected => "protected".to_string(),
+        swc_ecma_ast::Accessibility::Public => "public".to_string(),
+        _ => "".to_string(),
+      },
+      match node.kind {
+        swc_ecma_ast::MethodKind::Getter => "get ".to_string(),
+        swc_ecma_ast::MethodKind::Setter => "set ".to_string(),
+        _ => "".to_string(),
+      },
+      node.name,
+      render_params(function_def.params),
+      render_ts_type(function_def.return_type.unwrap())
+    ));
+  }
+  details.push_str("\n");
+  details
+}
+
+fn format_namespace_details(node: doc::DocNode) -> String {
+  let mut ns = String::new();
+
+  let elements = node.namespace_def.unwrap().elements;
+  for node in elements {
+    ns.push_str(&format_signature(&node, 0));
+  }
+  ns.push_str("\n");
+  ns
+}
+
+fn format_function_signature(node: &doc::DocNode, indent: i64) -> String {
+  format_indent(indent);
+  let function_def = node.function_def.clone().unwrap();
+  let return_type = function_def.return_type.unwrap();
+  format!(
+    "function {}({}): {}\n",
+    node.name,
+    render_params(function_def.params),
+    render_ts_type(return_type).as_str()
+  )
+}
+
+fn format_class_signature(node: &doc::DocNode, indent: i64) -> String {
+  format_indent(indent);
+  format!("class {}\n", node.name)
+}
+
+fn format_variable_signature(node: &doc::DocNode, indent: i64) -> String {
+  format_indent(indent);
+  let variable_def = node.variable_def.clone().unwrap();
+  format!(
+    "{} {}{}\n",
+    match variable_def.kind {
+      swc_ecma_ast::VarDeclKind::Const => "const".to_string(),
+      swc_ecma_ast::VarDeclKind::Let => "let".to_string(),
+      swc_ecma_ast::VarDeclKind::Var => "var".to_string(),
+    },
+    node.name,
+    if variable_def.ts_type.is_some() {
+      format!(": {}", render_ts_type(variable_def.ts_type.unwrap()))
+    } else {
+      "".to_string()
+    }
+  )
+}
+
+fn format_enum_signature(node: &doc::DocNode, indent: i64) -> String {
+  format_indent(indent);
+  format!("enum {}\n", node.name)
+}
+
+fn format_interface_signature(node: &doc::DocNode, indent: i64) -> String {
+  format_indent(indent);
+  format!("interface {}\n", node.name)
+}
+
+fn format_type_alias_signature(node: &doc::DocNode, indent: i64) -> String {
+  format_indent(indent);
+  format!("type {}\n", node.name)
+}
+
+fn format_namespace_signature(node: &doc::DocNode, indent: i64) -> String {
+  format_indent(indent);
+  format!("namespace {}\n", node.name)
+}
diff --git a/cli/doc/tests.rs b/cli/doc/tests.rs
new file mode 100644
index 000000000..c9408e8cf
--- /dev/null
+++ b/cli/doc/tests.rs
@@ -0,0 +1,568 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use super::DocParser;
+use serde_json;
+use serde_json::json;
+
+#[test]
+fn export_fn() {
+  let source_code = r#"/**
+* Hello there, this is a multiline JSdoc.
+* 
+* It has many lines
+* 
+* Or not that many?
+*/
+export function foo(a: string, b: number): void {
+    console.log("Hello world");
+}
+"#;
+  let entries = DocParser::default()
+    .parse("test.ts".to_string(), source_code.to_string())
+    .unwrap();
+  assert_eq!(entries.len(), 1);
+  let entry = &entries[0];
+  let expected_json = json!({
+    "functionDef": {
+      "isAsync": false,
+      "isGenerator": false,
+      "params": [
+          {
+            "name": "a",
+            "tsType": {
+              "keyword": "string",
+              "kind": "keyword",
+              "repr": "string",
+            },
+          },
+          {
+            "name": "b",
+            "tsType": {
+              "keyword": "number",
+              "kind": "keyword",
+              "repr": "number",
+            },
+          },
+      ],
+      "returnType": {
+        "keyword": "void",
+        "kind": "keyword",
+        "repr": "void",
+      },
+    },
+    "jsDoc": "Hello there, this is a multiline JSdoc.\n\nIt has many lines\n\nOr not that many?",
+    "kind": "function",
+    "location": {
+      "col": 0,
+      "filename": "test.ts",
+      "line": 8,
+    },
+    "name": "foo",
+  });
+  let actual = serde_json::to_value(entry).unwrap();
+  assert_eq!(actual, expected_json);
+
+  assert!(super::printer::format(entries).contains("Hello there"));
+}
+
+#[test]
+fn export_const() {
+  let source_code =
+    "/** Something about fizzBuzz */\nexport const fizzBuzz = \"fizzBuzz\";\n";
+  let entries = DocParser::default()
+    .parse("test.ts".to_string(), source_code.to_string())
+    .unwrap();
+  assert_eq!(entries.len(), 1);
+  let entry = &entries[0];
+  let expected_json = json!({
+    "kind": "variable",
+    "name": "fizzBuzz",
+    "location": {
+      "filename": "test.ts",
+      "line": 2,
+      "col": 0
+    },
+    "jsDoc": "Something about fizzBuzz",
+    "variableDef": {
+      "tsType": null,
+      "kind": "const"
+    }
+  });
+  let actual = serde_json::to_value(entry).unwrap();
+  assert_eq!(actual, expected_json);
+
+  assert!(super::printer::format(entries).contains("Something about fizzBuzz"));
+}
+
+#[test]
+fn export_class() {
+  let source_code = r#"
+/** Class doc */
+export class Foobar extends Fizz implements Buzz {
+    private private1: boolean;
+    protected protected1: number;
+    public public1: boolean;
+    public2: number;
+
+    /** Constructor js doc */
+    constructor(name: string, private private2: number, protected protected2: number) {}
+
+    /** Async foo method */
+    async foo(): Promise<void> {
+        //
+    }
+
+    /** Sync bar method */
+    bar(): void {
+        //
+    }
+}
+"#;
+  let entries = DocParser::default()
+    .parse("test.ts".to_string(), source_code.to_string())
+    .unwrap();
+  assert_eq!(entries.len(), 1);
+  let expected_json = json!({
+    "kind": "class",
+    "name": "Foobar",
+    "location": {
+      "filename": "test.ts",
+      "line": 3,
+      "col": 0
+    },
+    "jsDoc": "Class doc",
+    "classDef": {
+      "isAbstract": false,
+      "constructors": [
+        {
+          "jsDoc": "Constructor js doc",
+          "accessibility": null,
+          "name": "constructor",
+          "params": [
+            {
+              "name": "name",
+              "tsType": {
+                "repr": "string",
+                "kind": "keyword",
+                "keyword": "string"
+              }
+            },
+            {
+              "name": "<TODO>",
+              "tsType": null
+            },
+            {
+              "name": "<TODO>",
+              "tsType": null
+            }
+          ],
+          "location": {
+            "filename": "test.ts",
+            "line": 10,
+            "col": 4
+          }
+        }
+      ],
+      "properties": [
+        {
+          "jsDoc": null,
+          "tsType": {
+              "repr": "boolean",
+              "kind": "keyword",
+              "keyword": "boolean"
+          },
+          "readonly": false,
+          "accessibility": "private",
+          "isAbstract": false,
+          "isStatic": false,
+          "name": "private1",
+          "location": {
+            "filename": "test.ts",
+            "line": 4,
+            "col": 4
+          }
+        },
+        {
+          "jsDoc": null,
+          "tsType": {
+            "repr": "number",
+            "kind": "keyword",
+            "keyword": "number"
+          },
+          "readonly": false,
+          "accessibility": "protected",
+          "isAbstract": false,
+          "isStatic": false,
+          "name": "protected1",
+          "location": {
+            "filename": "test.ts",
+            "line": 5,
+            "col": 4
+          }
+        },
+        {
+          "jsDoc": null,
+          "tsType": {
+            "repr": "boolean",
+            "kind": "keyword",
+            "keyword": "boolean"
+          },
+          "readonly": false,
+          "accessibility": "public",
+          "isAbstract": false,
+          "isStatic": false,
+          "name": "public1",
+          "location": {
+            "filename": "test.ts",
+            "line": 6,
+            "col": 4
+          }
+        },
+        {
+          "jsDoc": null,
+          "tsType": {
+            "repr": "number",
+            "kind": "keyword",
+            "keyword": "number"
+          },
+          "readonly": false,
+          "accessibility": null,
+          "isAbstract": false,
+          "isStatic": false,
+          "name": "public2",
+          "location": {
+            "filename": "test.ts",
+            "line": 7,
+            "col": 4
+          }
+        }
+      ],
+      "methods": [
+        {
+          "jsDoc": "Async foo method",
+          "accessibility": null,
+          "isAbstract": false,
+          "isStatic": false,
+          "name": "foo",
+          "kind": "method",
+          "functionDef": {
+            "params": [],
+            "returnType": {
+                "repr": "Promise",
+                "kind": "typeRef",
+                "typeRef": {
+                  "typeParams": [
+                    {
+                      "repr": "void",
+                      "kind": "keyword",
+                      "keyword": "void"
+                    }
+                  ],
+                  "typeName": "Promise"
+                }
+            },
+            "isAsync": true,
+            "isGenerator": false
+          },
+          "location": {
+            "filename": "test.ts",
+            "line": 13,
+            "col": 4
+          }
+        },
+        {
+          "jsDoc": "Sync bar method",
+          "accessibility": null,
+          "isAbstract": false,
+          "isStatic": false,
+          "name": "bar",
+          "kind": "method",
+          "functionDef": {
+            "params": [],
+              "returnType": {
+                "repr": "void",
+                "kind": "keyword",
+                "keyword": "void"
+              },
+              "isAsync": false,
+              "isGenerator": false
+            },
+            "location": {
+              "filename": "test.ts",
+              "line": 18,
+              "col": 4
+            }
+          }
+      ]
+    }
+  });
+  let entry = &entries[0];
+  let actual = serde_json::to_value(entry).unwrap();
+  assert_eq!(actual, expected_json);
+
+  assert!(super::printer::format(entries).contains("class Foobar"));
+}
+
+#[test]
+fn export_interface() {
+  let source_code = r#"
+/**
+ * Interface js doc
+ */
+export interface Reader {
+    /** Read n bytes */
+    read(buf: Uint8Array, something: unknown): Promise<number>
+}
+    "#;
+  let entries = DocParser::default()
+    .parse("test.ts".to_string(), source_code.to_string())
+    .unwrap();
+  assert_eq!(entries.len(), 1);
+  let entry = &entries[0];
+  let expected_json = json!({
+      "kind": "interface",
+      "name": "Reader",
+      "location": {
+        "filename": "test.ts",
+        "line": 5,
+        "col": 0
+      },
+      "jsDoc": "Interface js doc",
+      "interfaceDef": {
+        "methods": [
+          {
+            "name": "read",
+            "location": {
+              "filename": "test.ts",
+              "line": 7,
+              "col": 4
+            },
+            "jsDoc": "Read n bytes",
+            "params": [
+              {
+                "name": "buf",
+                "tsType": {
+                  "repr": "Uint8Array",
+                  "kind": "typeRef",
+                  "typeRef": {
+                    "typeParams": null,
+                    "typeName": "Uint8Array"
+                  }
+                }
+              },
+              {
+                "name": "something",
+                "tsType": {
+                  "repr": "unknown",
+                  "kind": "keyword",
+                  "keyword": "unknown"
+                }
+              }
+            ],
+            "returnType": {
+              "repr": "Promise",
+              "kind": "typeRef",
+              "typeRef": {
+                "typeParams": [
+                  {
+                    "repr": "number",
+                    "kind": "keyword",
+                    "keyword": "number"
+                  }
+                ],
+                "typeName": "Promise"
+              }
+            }
+          }
+        ],
+        "properties": [],
+        "callSignatures": []
+    }
+  });
+  let actual = serde_json::to_value(entry).unwrap();
+  assert_eq!(actual, expected_json);
+
+  assert!(super::printer::format(entries).contains("interface Reader"));
+}
+
+#[test]
+fn export_type_alias() {
+  let source_code = r#"
+/** Array holding numbers */
+export type NumberArray = Array<number>;
+    "#;
+  let entries = DocParser::default()
+    .parse("test.ts".to_string(), source_code.to_string())
+    .unwrap();
+  assert_eq!(entries.len(), 1);
+  let entry = &entries[0];
+  let expected_json = json!({
+    "kind": "typeAlias",
+    "name": "NumberArray",
+    "location": {
+        "filename": "test.ts",
+      "line": 3,
+      "col": 0
+    },
+    "jsDoc": "Array holding numbers",
+    "typeAliasDef": {
+      "tsType": {
+        "repr": "Array",
+        "kind": "typeRef",
+        "typeRef": {
+          "typeParams": [
+            {
+              "repr": "number",
+              "kind": "keyword",
+              "keyword": "number"
+            }
+          ],
+          "typeName": "Array"
+        }
+      }
+    }
+  });
+  let actual = serde_json::to_value(entry).unwrap();
+  assert_eq!(actual, expected_json);
+
+  assert!(super::printer::format(entries).contains("Array holding numbers"));
+}
+
+#[test]
+fn export_enum() {
+  let source_code = r#"
+/**
+ * Some enum for good measure
+ */
+export enum Hello {
+    World = "world",
+    Fizz = "fizz",
+    Buzz = "buzz",
+}
+    "#;
+  let entries = DocParser::default()
+    .parse("test.ts".to_string(), source_code.to_string())
+    .unwrap();
+  assert_eq!(entries.len(), 1);
+  let entry = &entries[0];
+  let expected_json = json!({
+    "kind": "enum",
+    "name": "Hello",
+    "location": {
+      "filename": "test.ts",
+      "line": 5,
+      "col": 0
+    },
+    "jsDoc": "Some enum for good measure",
+    "enumDef": {
+      "members": [
+        {
+          "name": "World"
+        },
+        {
+          "name": "Fizz"
+        },
+        {
+          "name": "Buzz"
+        }
+      ]
+    }
+  });
+  let actual = serde_json::to_value(entry).unwrap();
+  assert_eq!(actual, expected_json);
+
+  assert!(super::printer::format(entries.clone())
+    .contains("Some enum for good measure"));
+  assert!(super::printer::format(entries).contains("enum Hello"));
+}
+
+#[test]
+fn export_namespace() {
+  let source_code = r#"
+/** Namespace JSdoc */
+export namespace RootNs {
+    export const a = "a";
+
+    /** Nested namespace JSDoc */
+    export namespace NestedNs {
+      export enum Foo {
+        a = 1,
+        b = 2,
+        c = 3,
+      }
+    }
+}
+    "#;
+  let entries = DocParser::default()
+    .parse("test.ts".to_string(), source_code.to_string())
+    .unwrap();
+  assert_eq!(entries.len(), 1);
+  let entry = &entries[0];
+  let expected_json = json!({
+    "kind": "namespace",
+    "name": "RootNs",
+    "location": {
+      "filename": "test.ts",
+      "line": 3,
+      "col": 0
+    },
+    "jsDoc": "Namespace JSdoc",
+    "namespaceDef": {
+      "elements": [
+        {
+          "kind": "variable",
+          "name": "a",
+          "location": {
+            "filename": "test.ts",
+            "line": 4,
+            "col": 4
+          },
+          "jsDoc": null,
+          "variableDef": {
+            "tsType": null,
+            "kind": "const"
+          }
+        },
+        {
+          "kind": "namespace",
+          "name": "NestedNs",
+          "location": {
+            "filename": "test.ts",
+            "line": 7,
+            "col": 4
+          },
+          "jsDoc": "Nested namespace JSDoc",
+          "namespaceDef": {
+            "elements": [
+              {
+                "kind": "enum",
+                "name": "Foo",
+                "location": {
+                  "filename": "test.ts",
+                  "line": 8,
+                  "col": 6
+                },
+                "jsDoc": null,
+                "enumDef": {
+                  "members": [
+                    {
+                      "name": "a"
+                    },
+                    {
+                      "name": "b"
+                    },
+                    {
+                      "name": "c"
+                    }
+                  ]
+                }
+              }
+            ]
+          }
+        }
+      ]
+    }
+  });
+  let actual = serde_json::to_value(entry).unwrap();
+  assert_eq!(actual, expected_json);
+  assert!(super::printer::format(entries).contains("namespace RootNs"));
+}
diff --git a/cli/doc/ts_type.rs b/cli/doc/ts_type.rs
new file mode 100644
index 000000000..9a7d191ba
--- /dev/null
+++ b/cli/doc/ts_type.rs
@@ -0,0 +1,821 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use super::ParamDef;
+use serde::Serialize;
+use swc_common::SourceMap;
+use swc_ecma_ast;
+use swc_ecma_ast::TsArrayType;
+use swc_ecma_ast::TsConditionalType;
+use swc_ecma_ast::TsFnOrConstructorType;
+use swc_ecma_ast::TsIndexedAccessType;
+use swc_ecma_ast::TsKeywordType;
+use swc_ecma_ast::TsLit;
+use swc_ecma_ast::TsLitType;
+use swc_ecma_ast::TsOptionalType;
+use swc_ecma_ast::TsParenthesizedType;
+use swc_ecma_ast::TsRestType;
+use swc_ecma_ast::TsThisType;
+use swc_ecma_ast::TsTupleType;
+use swc_ecma_ast::TsType;
+use swc_ecma_ast::TsTypeAnn;
+use swc_ecma_ast::TsTypeLit;
+use swc_ecma_ast::TsTypeOperator;
+use swc_ecma_ast::TsTypeQuery;
+use swc_ecma_ast::TsTypeRef;
+use swc_ecma_ast::TsUnionOrIntersectionType;
+
+// pub enum TsType {
+//  *      TsKeywordType(TsKeywordType),
+//  *      TsThisType(TsThisType),
+//  *      TsFnOrConstructorType(TsFnOrConstructorType),
+//  *      TsTypeRef(TsTypeRef),
+//  *      TsTypeQuery(TsTypeQuery),
+//  *      TsTypeLit(TsTypeLit),
+//  *      TsArrayType(TsArrayType),
+//  *      TsTupleType(TsTupleType),
+//  *      TsOptionalType(TsOptionalType),
+//  *      TsRestType(TsRestType),
+//  *      TsUnionOrIntersectionType(TsUnionOrIntersectionType),
+//  *      TsConditionalType(TsConditionalType),
+//     TsInferType(TsInferType),
+//  *      TsParenthesizedType(TsParenthesizedType),
+//  *      TsTypeOperator(TsTypeOperator),
+//  *      TsIndexedAccessType(TsIndexedAccessType),
+//     TsMappedType(TsMappedType),
+//  *      TsLitType(TsLitType),
+//     TsTypePredicate(TsTypePredicate),
+//     TsImportType(TsImportType),
+// }
+
+impl Into<TsTypeDef> for &TsLitType {
+  fn into(self) -> TsTypeDef {
+    let (repr, lit) = match &self.lit {
+      TsLit::Number(num) => (
+        format!("{}", num.value),
+        LiteralDef {
+          kind: LiteralDefKind::Number,
+          number: Some(num.value),
+          string: None,
+          boolean: None,
+        },
+      ),
+      TsLit::Str(str_) => (
+        str_.value.to_string(),
+        LiteralDef {
+          kind: LiteralDefKind::String,
+          number: None,
+          string: Some(str_.value.to_string()),
+          boolean: None,
+        },
+      ),
+      TsLit::Bool(bool_) => (
+        bool_.value.to_string(),
+        LiteralDef {
+          kind: LiteralDefKind::Boolean,
+          number: None,
+          string: None,
+          boolean: Some(bool_.value),
+        },
+      ),
+    };
+
+    TsTypeDef {
+      repr,
+      kind: Some(TsTypeDefKind::Literal),
+      literal: Some(lit),
+      ..Default::default()
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsArrayType {
+  fn into(self) -> TsTypeDef {
+    let ts_type_def: TsTypeDef = (&*self.elem_type).into();
+
+    TsTypeDef {
+      array: Some(Box::new(ts_type_def)),
+      kind: Some(TsTypeDefKind::Array),
+      ..Default::default()
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsTupleType {
+  fn into(self) -> TsTypeDef {
+    let mut type_defs = vec![];
+
+    for type_box in &self.elem_types {
+      let ts_type: &TsType = &(*type_box);
+      let def: TsTypeDef = ts_type.into();
+      type_defs.push(def)
+    }
+
+    TsTypeDef {
+      tuple: Some(type_defs),
+      kind: Some(TsTypeDefKind::Tuple),
+      ..Default::default()
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsUnionOrIntersectionType {
+  fn into(self) -> TsTypeDef {
+    use swc_ecma_ast::TsUnionOrIntersectionType::*;
+
+    match self {
+      TsUnionType(union_type) => {
+        let mut types_union = vec![];
+
+        for type_box in &union_type.types {
+          let ts_type: &TsType = &(*type_box);
+          let def: TsTypeDef = ts_type.into();
+          types_union.push(def);
+        }
+
+        TsTypeDef {
+          union: Some(types_union),
+          kind: Some(TsTypeDefKind::Union),
+          ..Default::default()
+        }
+      }
+      TsIntersectionType(intersection_type) => {
+        let mut types_intersection = vec![];
+
+        for type_box in &intersection_type.types {
+          let ts_type: &TsType = &(*type_box);
+          let def: TsTypeDef = ts_type.into();
+          types_intersection.push(def);
+        }
+
+        TsTypeDef {
+          intersection: Some(types_intersection),
+          kind: Some(TsTypeDefKind::Intersection),
+          ..Default::default()
+        }
+      }
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsKeywordType {
+  fn into(self) -> TsTypeDef {
+    use swc_ecma_ast::TsKeywordTypeKind::*;
+
+    let keyword_str = match self.kind {
+      TsAnyKeyword => "any",
+      TsUnknownKeyword => "unknown",
+      TsNumberKeyword => "number",
+      TsObjectKeyword => "object",
+      TsBooleanKeyword => "boolean",
+      TsBigIntKeyword => "bigint",
+      TsStringKeyword => "string",
+      TsSymbolKeyword => "symbol",
+      TsVoidKeyword => "void",
+      TsUndefinedKeyword => "undefined",
+      TsNullKeyword => "null",
+      TsNeverKeyword => "never",
+    };
+
+    TsTypeDef {
+      repr: keyword_str.to_string(),
+      kind: Some(TsTypeDefKind::Keyword),
+      keyword: Some(keyword_str.to_string()),
+      ..Default::default()
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsTypeOperator {
+  fn into(self) -> TsTypeDef {
+    let ts_type = (&*self.type_ann).into();
+    let type_operator_def = TsTypeOperatorDef {
+      operator: self.op.as_str().to_string(),
+      ts_type,
+    };
+
+    TsTypeDef {
+      type_operator: Some(Box::new(type_operator_def)),
+      kind: Some(TsTypeDefKind::TypeOperator),
+      ..Default::default()
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsParenthesizedType {
+  fn into(self) -> TsTypeDef {
+    let ts_type = (&*self.type_ann).into();
+
+    TsTypeDef {
+      parenthesized: Some(Box::new(ts_type)),
+      kind: Some(TsTypeDefKind::Parenthesized),
+      ..Default::default()
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsRestType {
+  fn into(self) -> TsTypeDef {
+    let ts_type = (&*self.type_ann).into();
+
+    TsTypeDef {
+      rest: Some(Box::new(ts_type)),
+      kind: Some(TsTypeDefKind::Rest),
+      ..Default::default()
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsOptionalType {
+  fn into(self) -> TsTypeDef {
+    let ts_type = (&*self.type_ann).into();
+
+    TsTypeDef {
+      optional: Some(Box::new(ts_type)),
+      kind: Some(TsTypeDefKind::Optional),
+      ..Default::default()
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsThisType {
+  fn into(self) -> TsTypeDef {
+    TsTypeDef {
+      repr: "this".to_string(),
+      this: Some(true),
+      kind: Some(TsTypeDefKind::This),
+      ..Default::default()
+    }
+  }
+}
+
+fn ts_entity_name_to_name(entity_name: &swc_ecma_ast::TsEntityName) -> String {
+  use swc_ecma_ast::TsEntityName::*;
+
+  match entity_name {
+    Ident(ident) => ident.sym.to_string(),
+    TsQualifiedName(ts_qualified_name) => {
+      let left = ts_entity_name_to_name(&ts_qualified_name.left);
+      let right = ts_qualified_name.right.sym.to_string();
+      format!("{}.{}", left, right)
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsTypeQuery {
+  fn into(self) -> TsTypeDef {
+    use swc_ecma_ast::TsTypeQueryExpr::*;
+
+    let type_name = match &self.expr_name {
+      TsEntityName(entity_name) => ts_entity_name_to_name(&*entity_name),
+      Import(import_type) => import_type.arg.value.to_string(),
+    };
+
+    TsTypeDef {
+      repr: type_name.to_string(),
+      type_query: Some(type_name),
+      kind: Some(TsTypeDefKind::TypeQuery),
+      ..Default::default()
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsTypeRef {
+  fn into(self) -> TsTypeDef {
+    let type_name = ts_entity_name_to_name(&self.type_name);
+
+    let type_params = if let Some(type_params_inst) = &self.type_params {
+      let mut ts_type_defs = vec![];
+
+      for type_box in &type_params_inst.params {
+        let ts_type: &TsType = &(*type_box);
+        let def: TsTypeDef = ts_type.into();
+        ts_type_defs.push(def);
+      }
+
+      Some(ts_type_defs)
+    } else {
+      None
+    };
+
+    TsTypeDef {
+      repr: type_name.to_string(),
+      type_ref: Some(TsTypeRefDef {
+        type_name,
+        type_params,
+      }),
+      kind: Some(TsTypeDefKind::TypeRef),
+      ..Default::default()
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsIndexedAccessType {
+  fn into(self) -> TsTypeDef {
+    let indexed_access_def = TsIndexedAccessDef {
+      readonly: self.readonly,
+      obj_type: Box::new((&*self.obj_type).into()),
+      index_type: Box::new((&*self.index_type).into()),
+    };
+
+    TsTypeDef {
+      indexed_access: Some(indexed_access_def),
+      kind: Some(TsTypeDefKind::IndexedAccess),
+      ..Default::default()
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsTypeLit {
+  fn into(self) -> TsTypeDef {
+    let mut methods = vec![];
+    let mut properties = vec![];
+    let mut call_signatures = vec![];
+
+    for type_element in &self.members {
+      use swc_ecma_ast::TsTypeElement::*;
+
+      match &type_element {
+        TsMethodSignature(ts_method_sig) => {
+          let mut params = vec![];
+
+          for param in &ts_method_sig.params {
+            use swc_ecma_ast::TsFnParam::*;
+
+            let param_def = match param {
+              Ident(ident) => {
+                let ts_type =
+                  ident.type_ann.as_ref().map(|rt| (&*rt.type_ann).into());
+
+                ParamDef {
+                  name: ident.sym.to_string(),
+                  ts_type,
+                }
+              }
+              _ => ParamDef {
+                name: "<TODO>".to_string(),
+                ts_type: None,
+              },
+            };
+
+            params.push(param_def);
+          }
+
+          let maybe_return_type = ts_method_sig
+            .type_ann
+            .as_ref()
+            .map(|rt| (&*rt.type_ann).into());
+
+          let method_def = LiteralMethodDef {
+            name: "<TODO>".to_string(),
+            params,
+            return_type: maybe_return_type,
+          };
+          methods.push(method_def);
+        }
+        TsPropertySignature(ts_prop_sig) => {
+          let name = match &*ts_prop_sig.key {
+            swc_ecma_ast::Expr::Ident(ident) => ident.sym.to_string(),
+            _ => "TODO".to_string(),
+          };
+
+          let mut params = vec![];
+
+          for param in &ts_prop_sig.params {
+            use swc_ecma_ast::TsFnParam::*;
+
+            let param_def = match param {
+              Ident(ident) => {
+                let ts_type =
+                  ident.type_ann.as_ref().map(|rt| (&*rt.type_ann).into());
+
+                ParamDef {
+                  name: ident.sym.to_string(),
+                  ts_type,
+                }
+              }
+              _ => ParamDef {
+                name: "<TODO>".to_string(),
+                ts_type: None,
+              },
+            };
+
+            params.push(param_def);
+          }
+
+          let ts_type = ts_prop_sig
+            .type_ann
+            .as_ref()
+            .map(|rt| (&*rt.type_ann).into());
+
+          let prop_def = LiteralPropertyDef {
+            name,
+            params,
+            ts_type,
+            computed: ts_prop_sig.computed,
+            optional: ts_prop_sig.optional,
+          };
+          properties.push(prop_def);
+        }
+        TsCallSignatureDecl(ts_call_sig) => {
+          let mut params = vec![];
+          for param in &ts_call_sig.params {
+            use swc_ecma_ast::TsFnParam::*;
+
+            let param_def = match param {
+              Ident(ident) => {
+                let ts_type =
+                  ident.type_ann.as_ref().map(|rt| (&*rt.type_ann).into());
+
+                ParamDef {
+                  name: ident.sym.to_string(),
+                  ts_type,
+                }
+              }
+              _ => ParamDef {
+                name: "<TODO>".to_string(),
+                ts_type: None,
+              },
+            };
+
+            params.push(param_def);
+          }
+
+          let ts_type = ts_call_sig
+            .type_ann
+            .as_ref()
+            .map(|rt| (&*rt.type_ann).into());
+
+          let call_sig_def = LiteralCallSignatureDef { params, ts_type };
+          call_signatures.push(call_sig_def);
+        }
+        // TODO:
+        TsConstructSignatureDecl(_) => {}
+        TsIndexSignature(_) => {}
+      }
+    }
+
+    let type_literal = TsTypeLiteralDef {
+      methods,
+      properties,
+      call_signatures,
+    };
+
+    TsTypeDef {
+      kind: Some(TsTypeDefKind::TypeLiteral),
+      type_literal: Some(type_literal),
+      ..Default::default()
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsConditionalType {
+  fn into(self) -> TsTypeDef {
+    let conditional_type_def = TsConditionalDef {
+      check_type: Box::new((&*self.check_type).into()),
+      extends_type: Box::new((&*self.extends_type).into()),
+      true_type: Box::new((&*self.true_type).into()),
+      false_type: Box::new((&*self.false_type).into()),
+    };
+
+    TsTypeDef {
+      kind: Some(TsTypeDefKind::Conditional),
+      conditional_type: Some(conditional_type_def),
+      ..Default::default()
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsFnOrConstructorType {
+  fn into(self) -> TsTypeDef {
+    use swc_ecma_ast::TsFnOrConstructorType::*;
+
+    let fn_def = match self {
+      TsFnType(ts_fn_type) => {
+        let mut params = vec![];
+
+        for param in &ts_fn_type.params {
+          use swc_ecma_ast::TsFnParam::*;
+
+          let param_def = match param {
+            Ident(ident) => {
+              let ts_type: Option<TsTypeDef> =
+                ident.type_ann.as_ref().map(|rt| {
+                  let type_box = &*rt.type_ann;
+                  (&*type_box).into()
+                });
+
+              ParamDef {
+                name: ident.sym.to_string(),
+                ts_type,
+              }
+            }
+            _ => ParamDef {
+              name: "<TODO>".to_string(),
+              ts_type: None,
+            },
+          };
+
+          params.push(param_def);
+        }
+
+        TsFnOrConstructorDef {
+          constructor: false,
+          ts_type: (&*ts_fn_type.type_ann.type_ann).into(),
+          params,
+        }
+      }
+      TsConstructorType(ctor_type) => {
+        let mut params = vec![];
+
+        for param in &ctor_type.params {
+          use swc_ecma_ast::TsFnParam::*;
+
+          let param_def = match param {
+            Ident(ident) => {
+              let ts_type: Option<TsTypeDef> =
+                ident.type_ann.as_ref().map(|rt| {
+                  let type_box = &*rt.type_ann;
+                  (&*type_box).into()
+                });
+
+              ParamDef {
+                name: ident.sym.to_string(),
+                ts_type,
+              }
+            }
+            _ => ParamDef {
+              name: "<TODO>".to_string(),
+              ts_type: None,
+            },
+          };
+
+          params.push(param_def);
+        }
+
+        TsFnOrConstructorDef {
+          constructor: true,
+          ts_type: (&*ctor_type.type_ann.type_ann).into(),
+          params: vec![],
+        }
+      }
+    };
+
+    TsTypeDef {
+      kind: Some(TsTypeDefKind::FnOrConstructor),
+      fn_or_constructor: Some(Box::new(fn_def)),
+      ..Default::default()
+    }
+  }
+}
+
+impl Into<TsTypeDef> for &TsType {
+  fn into(self) -> TsTypeDef {
+    use swc_ecma_ast::TsType::*;
+
+    match self {
+      TsKeywordType(ref keyword_type) => keyword_type.into(),
+      TsLitType(ref lit_type) => lit_type.into(),
+      TsTypeRef(ref type_ref) => type_ref.into(),
+      TsUnionOrIntersectionType(union_or_inter) => union_or_inter.into(),
+      TsArrayType(array_type) => array_type.into(),
+      TsTupleType(tuple_type) => tuple_type.into(),
+      TsTypeOperator(type_op_type) => type_op_type.into(),
+      TsParenthesizedType(paren_type) => paren_type.into(),
+      TsRestType(rest_type) => rest_type.into(),
+      TsOptionalType(optional_type) => optional_type.into(),
+      TsTypeQuery(type_query) => type_query.into(),
+      TsThisType(this_type) => this_type.into(),
+      TsFnOrConstructorType(fn_or_con_type) => fn_or_con_type.into(),
+      TsConditionalType(conditional_type) => conditional_type.into(),
+      TsIndexedAccessType(indexed_access_type) => indexed_access_type.into(),
+      TsTypeLit(type_literal) => type_literal.into(),
+      _ => TsTypeDef {
+        repr: "<UNIMPLEMENTED>".to_string(),
+        ..Default::default()
+      },
+    }
+  }
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct TsTypeRefDef {
+  pub type_params: Option<Vec<TsTypeDef>>,
+  pub type_name: String,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub enum LiteralDefKind {
+  Number,
+  String,
+  Boolean,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct LiteralDef {
+  pub kind: LiteralDefKind,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub number: Option<f64>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub string: Option<String>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub boolean: Option<bool>,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct TsTypeOperatorDef {
+  pub operator: String,
+  pub ts_type: TsTypeDef,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct TsFnOrConstructorDef {
+  // TODO: type_params
+  pub constructor: bool,
+  pub ts_type: TsTypeDef,
+  pub params: Vec<ParamDef>,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct TsConditionalDef {
+  pub check_type: Box<TsTypeDef>,
+  pub extends_type: Box<TsTypeDef>,
+  pub true_type: Box<TsTypeDef>,
+  pub false_type: Box<TsTypeDef>,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct TsIndexedAccessDef {
+  pub readonly: bool,
+  pub obj_type: Box<TsTypeDef>,
+  pub index_type: Box<TsTypeDef>,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct LiteralMethodDef {
+  // TODO: type_params
+  pub name: String,
+  // pub location: Location,
+  // pub js_doc: Option<String>,
+  pub params: Vec<ParamDef>,
+  pub return_type: Option<TsTypeDef>,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct LiteralPropertyDef {
+  // TODO: type_params
+  pub name: String,
+  // pub location: Location,
+  // pub js_doc: Option<String>,
+  pub params: Vec<ParamDef>,
+  pub computed: bool,
+  pub optional: bool,
+  pub ts_type: Option<TsTypeDef>,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct LiteralCallSignatureDef {
+  // TODO: type_params
+  // pub location: Location,
+  // pub js_doc: Option<String>,
+  pub params: Vec<ParamDef>,
+  pub ts_type: Option<TsTypeDef>,
+}
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct TsTypeLiteralDef {
+  pub methods: Vec<LiteralMethodDef>,
+  pub properties: Vec<LiteralPropertyDef>,
+  pub call_signatures: Vec<LiteralCallSignatureDef>,
+}
+
+#[derive(Debug, PartialEq, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub enum TsTypeDefKind {
+  Keyword,
+  Literal,
+  TypeRef,
+  Union,
+  Intersection,
+  Array,
+  Tuple,
+  TypeOperator,
+  Parenthesized,
+  Rest,
+  Optional,
+  TypeQuery,
+  This,
+  FnOrConstructor,
+  Conditional,
+  IndexedAccess,
+  TypeLiteral,
+}
+
+#[derive(Debug, Default, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct TsTypeDef {
+  pub repr: String,
+
+  pub kind: Option<TsTypeDefKind>,
+
+  // TODO: make this struct more conrete
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub keyword: Option<String>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub literal: Option<LiteralDef>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub type_ref: Option<TsTypeRefDef>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub union: Option<Vec<TsTypeDef>>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub intersection: Option<Vec<TsTypeDef>>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub array: Option<Box<TsTypeDef>>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub tuple: Option<Vec<TsTypeDef>>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub type_operator: Option<Box<TsTypeOperatorDef>>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub parenthesized: Option<Box<TsTypeDef>>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub rest: Option<Box<TsTypeDef>>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub optional: Option<Box<TsTypeDef>>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub type_query: Option<String>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub this: Option<bool>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub fn_or_constructor: Option<Box<TsFnOrConstructorDef>>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub conditional_type: Option<TsConditionalDef>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub indexed_access: Option<TsIndexedAccessDef>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub type_literal: Option<TsTypeLiteralDef>,
+}
+
+pub fn ts_type_ann_to_def(
+  source_map: &SourceMap,
+  type_ann: &TsTypeAnn,
+) -> TsTypeDef {
+  use swc_ecma_ast::TsType::*;
+
+  match &*type_ann.type_ann {
+    TsKeywordType(keyword_type) => keyword_type.into(),
+    TsLitType(lit_type) => lit_type.into(),
+    TsTypeRef(type_ref) => type_ref.into(),
+    TsUnionOrIntersectionType(union_or_inter) => union_or_inter.into(),
+    TsArrayType(array_type) => array_type.into(),
+    TsTupleType(tuple_type) => tuple_type.into(),
+    TsTypeOperator(type_op_type) => type_op_type.into(),
+    TsParenthesizedType(paren_type) => paren_type.into(),
+    TsRestType(rest_type) => rest_type.into(),
+    TsOptionalType(optional_type) => optional_type.into(),
+    TsTypeQuery(type_query) => type_query.into(),
+    TsThisType(this_type) => this_type.into(),
+    TsFnOrConstructorType(fn_or_con_type) => fn_or_con_type.into(),
+    TsConditionalType(conditional_type) => conditional_type.into(),
+    TsIndexedAccessType(indexed_access_type) => indexed_access_type.into(),
+    TsTypeLit(type_literal) => type_literal.into(),
+    _ => {
+      let repr = source_map
+        .span_to_snippet(type_ann.span)
+        .expect("Class prop type not found");
+      let repr = repr.trim_start_matches(':').trim_start().to_string();
+
+      TsTypeDef {
+        repr,
+        ..Default::default()
+      }
+    }
+  }
+}
diff --git a/cli/doc/type_alias.rs b/cli/doc/type_alias.rs
new file mode 100644
index 000000000..3740aee84
--- /dev/null
+++ b/cli/doc/type_alias.rs
@@ -0,0 +1,25 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use serde::Serialize;
+use swc_ecma_ast;
+
+use super::parser::DocParser;
+use super::ts_type::TsTypeDef;
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct TypeAliasDef {
+  pub ts_type: TsTypeDef,
+  // TODO: type_params
+}
+
+pub fn get_doc_for_ts_type_alias_decl(
+  _doc_parser: &DocParser,
+  type_alias_decl: &swc_ecma_ast::TsTypeAliasDecl,
+) -> (String, TypeAliasDef) {
+  let alias_name = type_alias_decl.id.sym.to_string();
+  let ts_type = type_alias_decl.type_ann.as_ref().into();
+
+  let type_alias_def = TypeAliasDef { ts_type };
+
+  (alias_name, type_alias_def)
+}
diff --git a/cli/doc/variable.rs b/cli/doc/variable.rs
new file mode 100644
index 000000000..16bf26d25
--- /dev/null
+++ b/cli/doc/variable.rs
@@ -0,0 +1,43 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use serde::Serialize;
+use swc_ecma_ast;
+
+use super::parser::DocParser;
+use super::ts_type::ts_type_ann_to_def;
+use super::ts_type::TsTypeDef;
+
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct VariableDef {
+  pub ts_type: Option<TsTypeDef>,
+  pub kind: swc_ecma_ast::VarDeclKind,
+}
+
+pub fn get_doc_for_var_decl(
+  doc_parser: &DocParser,
+  var_decl: &swc_ecma_ast::VarDecl,
+) -> (String, VariableDef) {
+  assert!(!var_decl.decls.is_empty());
+  // TODO: support multiple declarators
+  let var_declarator = var_decl.decls.get(0).unwrap();
+
+  let var_name = match &var_declarator.name {
+    swc_ecma_ast::Pat::Ident(ident) => ident.sym.to_string(),
+    _ => "<TODO>".to_string(),
+  };
+
+  let maybe_ts_type = match &var_declarator.name {
+    swc_ecma_ast::Pat::Ident(ident) => ident
+      .type_ann
+      .as_ref()
+      .map(|rt| ts_type_ann_to_def(&doc_parser.source_map, rt)),
+    _ => None,
+  };
+
+  let variable_def = VariableDef {
+    ts_type: maybe_ts_type,
+    kind: var_decl.kind,
+  };
+
+  (var_name, variable_def)
+}
diff --git a/cli/flags.rs b/cli/flags.rs
index 4f55d69ef..d90f1f3b9 100644
--- a/cli/flags.rs
+++ b/cli/flags.rs
@@ -31,6 +31,11 @@ pub enum DenoSubcommand {
   Completions {
     buf: Box<[u8]>,
   },
+  Doc {
+    json: bool,
+    source_file: String,
+    filter: Option<String>,
+  },
   Eval {
     code: String,
     as_typescript: bool,
@@ -258,6 +263,8 @@ pub fn flags_from_vec_safe(args: Vec<String>) -> clap::Result<Flags> {
     test_parse(&mut flags, m);
   } else if let Some(m) = matches.subcommand_matches("upgrade") {
     upgrade_parse(&mut flags, m);
+  } else if let Some(m) = matches.subcommand_matches("doc") {
+    doc_parse(&mut flags, m);
   } else {
     unimplemented!();
   }
@@ -311,6 +318,7 @@ If the flag is set, restrict these messages to errors.",
     .subcommand(test_subcommand())
     .subcommand(types_subcommand())
     .subcommand(upgrade_subcommand())
+    .subcommand(doc_subcommand())
     .long_about(DENO_HELP)
     .after_help(ENV_VARIABLES_HELP)
 }
@@ -550,6 +558,22 @@ fn upgrade_parse(flags: &mut Flags, matches: &clap::ArgMatches) {
   flags.subcommand = DenoSubcommand::Upgrade { dry_run, force };
 }
 
+fn doc_parse(flags: &mut Flags, matches: &clap::ArgMatches) {
+  reload_arg_parse(flags, matches);
+  let source_file = matches.value_of("source_file").map(String::from).unwrap();
+  let json = matches.is_present("json");
+  let filter = if matches.is_present("filter") {
+    Some(matches.value_of("filter").unwrap().to_string())
+  } else {
+    None
+  };
+  flags.subcommand = DenoSubcommand::Doc {
+    source_file,
+    json,
+    filter,
+  };
+}
+
 fn types_subcommand<'a, 'b>() -> App<'a, 'b> {
   SubCommand::with_name("types")
     .about("Print runtime TypeScript declarations")
@@ -770,6 +794,43 @@ and is used to replace the current executable.",
     )
 }
 
+fn doc_subcommand<'a, 'b>() -> App<'a, 'b> {
+  SubCommand::with_name("doc")
+    .about("Show documentation for module")
+    .long_about(
+      "Show documentation for module.
+
+Output documentation to terminal:
+    deno doc ./path/to/module.ts
+
+Show detail of symbol:
+    deno doc ./path/to/module.ts MyClass.someField
+
+Output documentation in JSON format:
+    deno doc --json ./path/to/module.ts",
+    )
+    .arg(reload_arg())
+    .arg(
+      Arg::with_name("json")
+        .long("json")
+        .help("Output documentation in JSON format.")
+        .takes_value(false),
+    )
+    .arg(
+      Arg::with_name("source_file")
+        .takes_value(true)
+        .required(true),
+    )
+    .arg(
+      Arg::with_name("filter")
+        .help("Dot separated path to symbol.")
+        .takes_value(true)
+        .required(false)
+        .conflicts_with("json")
+        .conflicts_with("pretty"),
+    )
+}
+
 fn permission_args<'a, 'b>(app: App<'a, 'b>) -> App<'a, 'b> {
   app
     .arg(
@@ -1219,6 +1280,7 @@ fn arg_hacks(mut args: Vec<String>) -> Vec<String> {
   let subcommands = sset![
     "bundle",
     "completions",
+    "doc",
     "eval",
     "fetch",
     "fmt",
@@ -2380,6 +2442,41 @@ fn repl_with_cafile() {
 }
 
 #[test]
+fn doc() {
+  let r =
+    flags_from_vec_safe(svec!["deno", "doc", "--json", "path/to/module.ts"]);
+  assert_eq!(
+    r.unwrap(),
+    Flags {
+      subcommand: DenoSubcommand::Doc {
+        json: true,
+        source_file: "path/to/module.ts".to_string(),
+        filter: None,
+      },
+      ..Flags::default()
+    }
+  );
+
+  let r = flags_from_vec_safe(svec![
+    "deno",
+    "doc",
+    "path/to/module.ts",
+    "SomeClass.someField"
+  ]);
+  assert_eq!(
+    r.unwrap(),
+    Flags {
+      subcommand: DenoSubcommand::Doc {
+        json: false,
+        source_file: "path/to/module.ts".to_string(),
+        filter: Some("SomeClass.someField".to_string()),
+      },
+      ..Flags::default()
+    }
+  );
+}
+
+#[test]
 fn inspect_default_host() {
   let r = flags_from_vec_safe(svec!["deno", "run", "--inspect", "foo.js"]);
   assert_eq!(
diff --git a/cli/lib.rs b/cli/lib.rs
index 7b5b56ba2..11ab26626 100644
--- a/cli/lib.rs
+++ b/cli/lib.rs
@@ -27,6 +27,7 @@ pub mod compilers;
 pub mod deno_dir;
 pub mod diagnostics;
 mod disk_cache;
+mod doc;
 mod file_fetcher;
 pub mod flags;
 mod fmt;
@@ -111,6 +112,18 @@ impl log::Log for Logger {
   fn flush(&self) {}
 }
 
+fn write_to_stdout_ignore_sigpipe(bytes: &[u8]) -> Result<(), std::io::Error> {
+  use std::io::ErrorKind;
+
+  match std::io::stdout().write_all(bytes) {
+    Ok(()) => Ok(()),
+    Err(e) => match e.kind() {
+      ErrorKind::BrokenPipe => Ok(()),
+      _ => Err(e),
+    },
+  }
+}
+
 fn create_main_worker(
   global_state: GlobalState,
   main_module: ModuleSpecifier,
@@ -344,6 +357,57 @@ async fn bundle_command(
   bundle_result
 }
 
+async fn doc_command(
+  flags: Flags,
+  source_file: String,
+  json: bool,
+  maybe_filter: Option<String>,
+) -> Result<(), ErrBox> {
+  let global_state = GlobalState::new(flags.clone())?;
+  let module_specifier =
+    ModuleSpecifier::resolve_url_or_path(&source_file).unwrap();
+  let source_file = global_state
+    .file_fetcher
+    .fetch_source_file(&module_specifier, None)
+    .await?;
+  let source_code = String::from_utf8(source_file.source_code)?;
+
+  let doc_parser = doc::DocParser::default();
+  let parse_result =
+    doc_parser.parse(module_specifier.to_string(), source_code);
+
+  let doc_nodes = match parse_result {
+    Ok(nodes) => nodes,
+    Err(e) => {
+      eprintln!("Failed to parse documentation:");
+      for diagnostic in e {
+        eprintln!("{}", diagnostic.message());
+      }
+
+      std::process::exit(1);
+    }
+  };
+
+  if json {
+    let writer = std::io::BufWriter::new(std::io::stdout());
+    serde_json::to_writer_pretty(writer, &doc_nodes).map_err(ErrBox::from)
+  } else {
+    let details = if let Some(filter) = maybe_filter {
+      let node = doc::find_node_by_name_recursively(doc_nodes, filter.clone());
+      if let Some(node) = node {
+        doc::printer::format_details(node)
+      } else {
+        eprintln!("Node {} was not found!", filter);
+        std::process::exit(1);
+      }
+    } else {
+      doc::printer::format(doc_nodes)
+    };
+
+    write_to_stdout_ignore_sigpipe(details.as_bytes()).map_err(ErrBox::from)
+  }
+}
+
 async fn run_repl(flags: Flags) -> Result<(), ErrBox> {
   let main_module =
     ModuleSpecifier::resolve_url_or_path("./__$deno$repl.ts").unwrap();
@@ -451,6 +515,11 @@ pub fn main() {
       source_file,
       out_file,
     } => bundle_command(flags, source_file, out_file).boxed_local(),
+    DenoSubcommand::Doc {
+      source_file,
+      json,
+      filter,
+    } => doc_command(flags, source_file, json, filter).boxed_local(),
     DenoSubcommand::Eval {
       code,
       as_typescript,
@@ -478,7 +547,10 @@ pub fn main() {
       allow_none,
     } => test_command(flags, include, fail_fast, allow_none).boxed_local(),
     DenoSubcommand::Completions { buf } => {
-      print!("{}", std::str::from_utf8(&buf).unwrap());
+      if let Err(e) = write_to_stdout_ignore_sigpipe(&buf) {
+        eprintln!("{}", e);
+        std::process::exit(1);
+      }
       return;
     }
     DenoSubcommand::Types => {
@@ -488,8 +560,10 @@ pub fn main() {
         crate::js::SHARED_GLOBALS_LIB,
         crate::js::WINDOW_LIB
       );
-      // TODO(ry) Only ignore SIGPIPE. Currently ignoring all errors.
-      let _r = std::io::stdout().write_all(types.as_bytes());
+      if let Err(e) = write_to_stdout_ignore_sigpipe(types.as_bytes()) {
+        eprintln!("{}", e);
+        std::process::exit(1);
+      }
       return;
     }
     DenoSubcommand::Upgrade { force, dry_run } => {