Fix issues with JavaScript importing JavaScript. (#4120)

Fixes #3852
Fixes #4117

7 files changed, 20 insertions, 5 deletions

diff --git a/cli/js/compiler_host.ts b/cli/js/compiler_host.ts
index d44bc7a03..78ed4889a 100644
--- a/cli/js/compiler_host.ts
+++ b/cli/js/compiler_host.ts
@@ -47,18 +47,18 @@ export const defaultBundlerOptions: ts.CompilerOptions = {
 
 /** Default options used by the compiler Host when compiling. */
 export const defaultCompileOptions: ts.CompilerOptions = {
-  allowJs: true,
+  allowJs: false,
   allowNonTsExtensions: true,
-  strict: true,
   checkJs: false,
   esModuleInterop: true,
+  jsx: ts.JsxEmit.React,
   module: ts.ModuleKind.ESNext,
   outDir: OUT_DIR,
   resolveJsonModule: true,
   sourceMap: true,
+  strict: true,
   stripComments: true,
-  target: ts.ScriptTarget.ESNext,
-  jsx: ts.JsxEmit.React
+  target: ts.ScriptTarget.ESNext
 };
 
 /** Options that need to be used when doing a runtime (non bundled) compilation */
diff --git a/cli/js/compiler_util.ts b/cli/js/compiler_util.ts
index a28e2d109..6da38ab3b 100644
--- a/cli/js/compiler_util.ts
+++ b/cli/js/compiler_util.ts
@@ -304,7 +304,11 @@ export const ignoredDiagnostics = [
   // support JSON imports.  Allegedly this was fixed in
   // Microsoft/TypeScript#26825 but that doesn't seem to be working here,
   // so we will ignore complaints about this compiler setting.
-  5070
+  5070,
+  // TS7016: Could not find a declaration file for module '...'. '...'
+  // implicitly has an 'any' type.  This is due to `allowJs` being off by
+  // default but importing of a JavaScript module.
+  7016
 ];
 
 /** When doing a host configuration, processing the response and logging out
diff --git a/cli/tests/038_checkjs.tsconfig.json b/cli/tests/038_checkjs.tsconfig.json
index 08ac60b6c..46d96db9e 100644
--- a/cli/tests/038_checkjs.tsconfig.json
+++ b/cli/tests/038_checkjs.tsconfig.json
@@ -1,5 +1,6 @@
 {
   "compilerOptions": {
+    "allowJs": true,
     "checkJs": true
   }
 }
diff --git a/cli/tests/fix_js_import_js.ts b/cli/tests/fix_js_import_js.ts
new file mode 100644
index 000000000..c9f341748
--- /dev/null
+++ b/cli/tests/fix_js_import_js.ts
@@ -0,0 +1,3 @@
+import { isMod4 } from "./subdir/mod6.js";
+
+console.log(isMod4);
diff --git a/cli/tests/fix_js_import_js.ts.out b/cli/tests/fix_js_import_js.ts.out
new file mode 100644
index 000000000..27ba77dda
--- /dev/null
+++ b/cli/tests/fix_js_import_js.ts.out
@@ -0,0 +1 @@
+true
diff --git a/cli/tests/integration_tests.rs b/cli/tests/integration_tests.rs
index 1767be7c2..ccc571331 100644
--- a/cli/tests/integration_tests.rs
+++ b/cli/tests/integration_tests.rs
@@ -1160,6 +1160,11 @@ itest!(cafile_info {
   http_server: true,
 });
 
+itest!(fix_js_import_js {
+  args: "run --reload fix_js_import_js.ts",
+  output: "fix_js_import_js.ts.out",
+});
+
 itest!(fix_js_imports {
   args: "run --reload fix_js_imports.ts",
   output: "fix_js_imports.ts.out",
diff --git a/cli/tests/subdir/mod6.js b/cli/tests/subdir/mod6.js
new file mode 100644
index 000000000..5e17c9ee0
--- /dev/null
+++ b/cli/tests/subdir/mod6.js
@@ -0,0 +1 @@
+export { isMod4 } from "./mod4.js";