esm-loader-typescript

esm-loader-typescript

Node.js ESModule Loader for importing and loading Typescript (.ts) files and transpiling on the fly.

Warning! Using experimental Node.js features and flags, API will likely change. This may be helpful for development and testing, but should not be used in production.

Usage

npm install --save-dev esm-loader-typescript

We want to import a .ts file with Node.js:

// index.ts
const words: string = 'hello'
console.log(words)
// 'hello'

Config

If a tsconfig.json file is found, it will be loaded and used. Otherwise, we provide a bare-bones default config which will be used instead.

Standalone

NODE_OPTIONS="--experimental-loader esm-loader-typescript" node index.ts

Chainable

This loader can be configured, and chained with other loaders, using node-esm-loader. This should be your only loader handling Typescript files.

npm install --save-dev node-esm-loader

// .loaderrc.js
export default {
  loaders: ['esm-loader-typescript'],
}

NODE_OPTIONS="--experimental-loader node-esm-loader" node index.ts

Option: Debug

// .loaderrc.js
export default {
  loaders: [
    {
      loader: 'esm-loader-typescript',
      options: {
        debug: true,
      },
    },
  ],
}

Related

• esm-loader-import-relative-add-extension: Typescript usually generates .js files, so relative imports are suggested to have no file extension. But in our case, since we're transpiling on-the-fly, these extensionless imports leave Node.js confused. Use this loader to add .ts extensions to any relative imports which are missing them, allowing Node.js to resolve and load the files.

License

MIT