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Support type checking .cjs files #38784
Description
Search Terms
- cjs
- cjs extension
- cjs files
Suggestion
Treat files with the .cjs file extension the same as the .js file extension, but disallowing ES Module syntax within them.
Use Cases
In packages with:
"type": "module",in package.json, Node loads all .js files as ES modules.
To load a file as a CommonJS module, one has to use the .cjs file extension.
Examples
// foo.cjs
// $ExpectType typeof Bar
const Bar = require("./bar.cjs");📝 Note: In order to currently have typed
.cjsimports, this file has to be namedbar.cjs.d.ts:
// bar.d.ts
declare class Bar {
constructor();
}
export = Bar;// bar.cjs
module.exports = class Bar {
constructor() {
// do stuff
}
};Checklist
My suggestion meets these guidelines:
- This wouldn't be a breaking change in existing TypeScript/JavaScript code
- This wouldn't change the runtime behavior of existing JavaScript code
- This could be implemented without emitting different JS based on the types of the expressions
- This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
- This feature would agree with the rest of TypeScript's Design Goals.
Activity
frank-dspeed commentedon Aug 7, 2020
If some one does want to test #39840 https://github.com/stealify/typescript
npm i -g vscode-typescript@https://github.com/stealify/typescript # Getting global path npm root -gHit f1 on keyboard open user settings and set
restart is not needed.
Raynos commentedon Feb 1, 2021
I would like to use the
.cjs&.mjsextensions with typescript as well. All three of these files are JavaScript files.a-ejs commentedon Feb 10, 2021
Agreed, seems odd that this isn't supported (or even planned?) yet.
hariombalhara commentedon Apr 30, 2021
For people coming to this thread, you can add
//@ts-checkat the top of a .cjs file to enable type checking for it.ExE-Boss commentedon Oct 12, 2021
Fixed in #45884 (TypeScript 4.5)