resolve-typescript-plugin

webpack plugin to resolve TypeScript files when importing with js file extension in ESM projects

Usage no npm install needed!

<script type="module">
  import resolveTypescriptPlugin from 'https://cdn.skypack.dev/resolve-typescript-plugin';
</script>

README

resolve-typescript-plugin

A webpack plugin to resolve TypeScript files imported using the .js extension when using ESM imports.

Why?

If you are using webpack in conjunction with TypeScript and ES Modules, you need this plugin for full compliance with the ES Modules ecosystem.

ES Modules require imports to specify the runtime path of the file to be imported, including file extension. For TypeScript files, this means that you must import using the extension .js even though the source file uses the extension .ts or .tsx. This is because TypeScript compiles to a .js file that will be used at runtime.

However, webpack behaves differently, even when configured for ES Modules. webpack expects that files will be imported by specifying the compile-time path of the file, including the compile-time extension. For TypeScript files this will be .ts or .tsx. Alternatively, webpack expects that files will be imported with no extension, in which case webpack will resolve the extension automatically according to the resolve.extensions option. Neither of these behaviours is consistent with browser or node ES Module environments.

This plugin extends webpack module resolution so that imports specifying a .js extension will resolve to the corresponding .ts or .tsx file if available, and fall back to .js otherwise.

If you want to create ES Modules in TypeScript that are consistent between webpack, browser, and node environments, use this plugin.

See ts-loader#1110 for more background on this issue.

Install

With npm:

npm install --save-dev resolve-typescript-plugin

or yarn:

yarn add --dev resolve-typescript-plugin

Usage

Include the following in package.json to configure your project to be an ES Module:

{
    "type": "module"
}

Include something like the following in webpack.config.js:

const ResolveTypeScriptPlugin = require("resolve-typescript-plugin").default;

exports = {
    module: {
        rules: [
            {
                test: /\.tsx?$/,
                use: "ts-loader"
            }
        ]
    },
    resolve: {
        plugins: [new ResolveTypeScriptPlugin()]
    }
};

You will also need to have ts-loader (or another TypeScript loader) installed and configured.

Previous versions of this README recommended setting resolve.fullySpecified to true. This is no longer recommended because it breaks compatibility with webpack-dev-server and possibly other webpack tooling.

If you use this plugin, you should probably remove .ts and .tsx from resolve.extensions.

Options

Pass options to the plugin as an argument to the constructor, as follows:

new ResolveTypeScriptPlugin({
    includeNodeModules: false
});

includeNodeModules

By default, the plugin does not resolve TypeScript files inside node_modules subdirectories. To enable this, set includeNodeModules: true.

Default: false.

Feedback

We're seeking community feedback on this plugin.

Please report bugs, problems, and missing features on the GitHub Issue Tracker.