1 files changed, 17 insertions, 1 deletions
diff --git a/core/extensions.rs b/core/extensions.rs
index 129e7b62a..b981e6da2 100644
--- a/core/extensions.rs
+++ b/core/extensions.rs
@@ -38,6 +38,7 @@ impl OpDecl {
 #[derive(Default)]
 pub struct Extension {
   js_files: Option<Vec<SourcePair>>,
+  esm_files: Option<Vec<SourcePair>>,
   ops: Option<Vec<OpDecl>>,
   opstate_fn: Option<Box<OpStateFn>>,
   middleware_fn: Option<Box<OpMiddlewareFn>>,
@@ -81,13 +82,20 @@ impl Extension {
 
   /// returns JS source code to be loaded into the isolate (either at snapshotting,
   /// or at startup).  as a vector of a tuple of the file name, and the source code.
-  pub fn init_js(&self) -> &[SourcePair] {
+  pub fn get_js_sources(&self) -> &[SourcePair] {
     match &self.js_files {
       Some(files) => files,
       None => &[],
     }
   }
 
+  pub fn get_esm_sources(&self) -> &[SourcePair] {
+    match &self.esm_files {
+      Some(files) => files,
+      None => &[],
+    }
+  }
+
   /// Called at JsRuntime startup to initialize ops in the isolate.
   pub fn init_ops(&mut self) -> Option<Vec<OpDecl>> {
     // TODO(@AaronO): maybe make op registration idempotent
@@ -145,6 +153,7 @@ impl Extension {
 #[derive(Default)]
 pub struct ExtensionBuilder {
   js: Vec<SourcePair>,
+  esm: Vec<SourcePair>,
   ops: Vec<OpDecl>,
   state: Option<Box<OpStateFn>>,
   middleware: Option<Box<OpMiddlewareFn>>,
@@ -164,6 +173,11 @@ impl ExtensionBuilder {
     self
   }
 
+  pub fn esm(&mut self, js_files: Vec<SourcePair>) -> &mut Self {
+    self.esm.extend(js_files);
+    self
+  }
+
   pub fn ops(&mut self, ops: Vec<OpDecl>) -> &mut Self {
     self.ops.extend(ops);
     self
@@ -195,10 +209,12 @@ impl ExtensionBuilder {
 
   pub fn build(&mut self) -> Extension {
     let js_files = Some(std::mem::take(&mut self.js));
+    let esm_files = Some(std::mem::take(&mut self.esm));
     let ops = Some(std::mem::take(&mut self.ops));
     let deps = Some(std::mem::take(&mut self.deps));
     Extension {
       js_files,
+      esm_files,
       ops,
       opstate_fn: self.state.take(),
       middleware_fn: self.middleware.take(),