# Pure ESM package The package that linked you here is now pure [ESM](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules). It cannot be `require()`'d from CommonJS. This means you have the following choices: 1. Use ESM yourself. **(preferred)**\ Use `import foo from 'foo'` instead of `const foo = require('foo')` to import the package. You also need to put `"type": "module"` in your package.json and more. Follow the below guide. 2. If the package is used in an async context, you could use [`await import(…)`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import#dynamic_imports) from CommonJS instead of `require(…)`. 3. Stay on the existing version of the package until you can move to ESM. 4. Since [Node.js 22](https://nodejs.org/en/blog/announcements/v22-release-announce#support-requireing-synchronous-esm-graphs), you may be able to `require()` ESM modules. However, I **strongly recommend moving to ESM instead**. **You also need to make sure you're on the latest minor version of Node.js. At minimum Node.js 16.** I would strongly recommend moving to ESM. ESM can still import CommonJS packages, but CommonJS packages cannot import ESM packages synchronously. **My repos are not the place to ask ESM/TypeScript/Webpack/Jest/ts-node/CRA support questions.** ## FAQ ### How can I move my CommonJS project to ESM? - Add `"type": "module"` to your package.json. - Replace `"main": "index.js"` with `"exports": "./index.js"` in your package.json. - Update the `"engines"` field in package.json to Node.js 18: `"node": ">=18"`. - Remove `'use strict';` from all JavaScript files. - Replace all `require()`/`module.export` with `import`/`export`. - Use only full relative file paths for imports: `import x from '.';` → `import x from './index.js';`. - If you have a TypeScript type definition (for example, `index.d.ts`), update it to use ESM imports/exports. - Use the [`node:` protocol](https://nodejs.org/api/esm.html#esm_node_imports) for Node.js built-in imports. Sidenote: If you're looking for guidance on how to add types to your JavaScript package, [check out my guide](https://github.com/sindresorhus/typescript-definition-style-guide). ### Can I import ESM packages in my TypeScript project? Yes, but you need to convert your project to output ESM. See below. ### How can I make my TypeScript project output ESM? [Read the official ESM guide.](https://www.typescriptlang.org/docs/handbook/esm-node.html) Quick steps: - Make sure you are using TypeScript 4.7 or later. - Add `"type": "module"` to your package.json. - Replace `"main": "index.js"` with `"exports": "./index.js"` in your package.json. - Update the `"engines"` field in package.json to Node.js 18: `"node": ">=18"`. - Add [`"module": "node16", "moduleResolution": "node16"`](https://www.typescriptlang.org/tsconfig#module) to your tsconfig.json. *([Example](https://github.com/sindresorhus/tsconfig/blob/main/tsconfig.json))* - **`moduleResolution` must be set to `node16` or `nodenext`, NOT `node`!** - Use only full relative file paths for imports: `import x from '.';` → `import x from './index.js';`. - Remove `namespace` usage and use `export` instead. - Use the [`node:` protocol](https://nodejs.org/api/esm.html#esm_node_imports) for Node.js built-in imports. - **You must use a `.js` extension in relative imports even though you're importing `.ts` files.** If you use `ts-node`, follow [this guide](https://github.com/TypeStrong/ts-node/issues/1007). [Example config.](https://github.com/sindresorhus/got/blob/5f278d74125608b7abe75941cb6a71e21e0fb892/tsconfig.json#L17-L21) ### How can I import ESM in Electron? Electron supports ESM as of Electron 28. [Please read this.](https://github.com/electron/electron/blob/main/docs/tutorial/esm.md) ### I'm having problems with ESM and Webpack The problem is either Webpack or your Webpack configuration. First, ensure you are on the latest version of Webpack. Please don't open an issue on my repo. Try asking on Stack Overflow or [open an issue the Webpack repo](https://github.com/webpack/webpack). ### I'm having problems with ESM and Next.js Upgrade to [Next.js 12](https://nextjs.org/blog/next-12#es-modules-support-and-url-imports) which has full ESM support. ### I'm having problems with ESM and Jest [Read this.](https://jestjs.io/docs/ecmascript-modules) ### I'm having problems with ESM and TypeScript If you have decided to make your project ESM (`"type": "module"` in your package.json), make sure you have [`"module": "node16"`](https://www.typescriptlang.org/tsconfig#module) in your tsconfig.json and that all your import statements to local files use the `.js` extension, **not** `.ts` or no extension. ### I'm having problems with ESM and `ts-node` **I would recommend [`tsx`](https://github.com/privatenumber/tsx) instead.** Follow [this guide](https://github.com/TypeStrong/ts-node/issues/1007) and ensure you are on the latest version of `ts-node`. [Example config.](https://github.com/sindresorhus/got/blob/5f278d74125608b7abe75941cb6a71e21e0fb892/tsconfig.json#L17-L21) ### I'm having problems with ESM and Create React App Create React App doesn't yet fully support ESM. I would recommend opening an issue on their repo with the problem you have encountered. One known issue is [#10933](https://github.com/facebook/create-react-app/issues/10933). ### How can I use TypeScript with AVA for an ESM project? Follow [this guide](https://github.com/avajs/ava/blob/main/docs/recipes/typescript.md#for-packages-with-type-module). ### How can I make sure I don't accidentally use CommonJS-specific conventions? We got you covered with this [ESLint rule](https://github.com/sindresorhus/eslint-plugin-unicorn/blob/main/docs/rules/prefer-module.md). You should also use [this rule](https://github.com/sindresorhus/eslint-plugin-unicorn/blob/main/docs/rules/prefer-node-protocol.md). ### What do I use instead of `__dirname` and `__filename`? **Node.js 20.11+** Use [`import.meta.dirname`](https://nodejs.org/api/esm.html#importmetadirname) and [`import.meta.filename`](https://nodejs.org/api/esm.html#importmetafilename). **Older Node.js versions** ```js import {fileURLToPath} from 'node:url'; import path from 'node:path'; const __filename = fileURLToPath(import.meta.url); const __dirname = path.dirname(fileURLToPath(import.meta.url)); ``` However, in most cases, this is better: ```js import {fileURLToPath} from 'node:url'; const foo = fileURLToPath(new URL('foo.js', import.meta.url)); ``` And many Node.js APIs accept URL directly, so you can just do this: ```js const foo = new URL('foo.js', import.meta.url); ``` ### How can I import a module and bypass the cache for testing? There's no good way to do this yet. Not until we get [ESM loader hooks](https://github.com/nodejs/modules/issues/307). For now, this snippet can be useful: ```js const importFresh = async modulePath => import(`${modulePath}?x=${Date.now()}`); const chalk = (await importFresh('chalk')).default; ``` *Note: This will cause memory leaks, so only use it for testing, not in production. Also, it will only reload the imported module, not its dependencies.* ### How can I import JSON? **Node.js 18.20+** ```js import packageJson from './package.json' with {type: 'json'}; ``` **Older Node.js versions** ```js import fs from 'node:fs/promises'; const packageJson = JSON.parse(await fs.readFile('package.json')); ``` ### When should I use a default export or named exports? My general rule is that if something exports a single main thing, it should be a default export. Keep in mind that you can combine a default export with named exports when it makes sense: ```js import readJson, {JSONError} from 'read-json'; ``` Here, we had exported the main thing `readJson`, but we also exported an error as a named export. #### Asynchronous and synchronous API If your package has both an asynchronous and synchronous main API, I would recommend using named exports: ```js import {readJson, readJsonSync} from 'read-json'; ``` This makes it clear to the reader that the package exports multiple main APIs. We also follow the Node.js convention of suffixing the synchronous API with `Sync`. #### Readable named exports I have noticed a bad pattern of packages using overly generic names for named exports: ```js import {parse} from 'parse-json'; ``` This forces the consumer to either accept the ambiguous name (which might cause naming conflicts) or rename it: ```js import {parse as parseJson} from 'parse-json'; ``` Instead, make it easy for the user: ```js import {parseJson} from 'parse-json'; ``` #### Examples With ESM, I now prefer descriptive named exports more often than a namespace default export: CommonJS (before): ```js const isStream = require('is-stream'); isStream.writable(…); ``` ESM (now): ```js import {isWritableStream} from 'is-stream'; isWritableStream(…); ```