@rollup/plugin-typescript

What is @rollup/plugin-typescript?

@rollup/plugin-typescript is a Rollup plugin that allows you to seamlessly integrate TypeScript into your Rollup build process. It compiles TypeScript files and includes them in your bundle, making it easier to work with TypeScript in a Rollup-based project.

What are @rollup/plugin-typescript's main functionalities?

Basic TypeScript Compilation

This feature allows you to compile TypeScript files into JavaScript. The code sample demonstrates a basic Rollup configuration that compiles a TypeScript file located at 'src/index.ts' and outputs a bundled JavaScript file at 'dist/bundle.js'.

const typescript = require('@rollup/plugin-typescript');

module.exports = {
  input: 'src/index.ts',
  output: {
    file: 'dist/bundle.js',
    format: 'cjs'
  },
  plugins: [
    typescript()
  ]
};

Custom TypeScript Compiler Options

This feature allows you to specify custom TypeScript compiler options by providing a path to a custom tsconfig.json file. The code sample shows how to use a custom TypeScript configuration file named 'tsconfig.custom.json'.

const typescript = require('@rollup/plugin-typescript');

module.exports = {
  input: 'src/index.ts',
  output: {
    file: 'dist/bundle.js',
    format: 'cjs'
  },
  plugins: [
    typescript({
      tsconfig: 'tsconfig.custom.json'
    })
  ]
};

Type Checking

This feature enables type checking during the build process. The code sample demonstrates how to enable type checking by setting the 'check' option to true.

const typescript = require('@rollup/plugin-typescript');

module.exports = {
  input: 'src/index.ts',
  output: {
    file: 'dist/bundle.js',
    format: 'cjs'
  },
  plugins: [
    typescript({
      check: true
    })
  ]
};

Other packages similar to @rollup/plugin-typescript

rollup-plugin-typescript2

rollup-plugin-typescript2 is another Rollup plugin for integrating TypeScript. It offers more advanced features like incremental builds and better error reporting compared to @rollup/plugin-typescript. However, it may have a steeper learning curve due to its additional configuration options.

ts-loader

ts-loader is a TypeScript loader for Webpack. While it is not a Rollup plugin, it serves a similar purpose in the Webpack ecosystem by allowing you to compile TypeScript files. It is highly configurable and integrates well with Webpack's ecosystem.

babel-plugin-transform-typescript

babel-plugin-transform-typescript is a Babel plugin that allows you to compile TypeScript using Babel. This can be useful if you are already using Babel for other transformations and want to keep your build process consistent. However, it does not perform type checking.

README

@rollup/plugin-typescript

🍣 A Rollup plugin for seamless integration between Rollup and Typescript.

Requirements

This plugin requires an LTS Node version (v14.0.0+) and Rollup v2.14.0+. This plugin also requires at least TypeScript 3.7.

Install

Using npm:

npm install @rollup/plugin-typescript --save-dev

Note that both typescript and tslib are peer dependencies of this plugin that need to be installed separately.

Why?

See @rollup/plugin-babel.

Usage

Create a rollup.config.js configuration file and import the plugin:

// rollup.config.js
import typescript from '@rollup/plugin-typescript';

export default {
  input: 'src/index.ts',
  output: {
    dir: 'output',
    format: 'cjs'
  },
  plugins: [typescript()]
};

Then call rollup either via the CLI or the API.

Options

The plugin loads any compilerOptions from the tsconfig.json file by default. Passing options to the plugin directly overrides those options:

...
export default {
  input: './main.ts',
  plugins: [
      typescript({ compilerOptions: {lib: ["es5", "es6", "dom"], target: "es5"}})
  ]
}

The following options are unique to rollup-plugin-typescript:

exclude

Type: String | Array[...String]
Default: null

A picomatch pattern, or array of patterns, which specifies the files in the build the plugin should ignore. By default no files are ignored.

include

Type: String | Array[...String]
Default: null

A picomatch pattern, or array of patterns, which specifies the files in the build the plugin should operate on. By default all .ts and .tsx files are targeted.

filterRoot

Type: String | Boolean
Default: rootDir ?? tsConfig.compilerOptions.rootDir ?? process.cwd()

Optionally resolves the include and exclude patterns against a directory other than process.cwd(). If a String is specified, then the value will be used as the base directory. Relative paths will be resolved against process.cwd() first. If false, then the patterns will not be resolved against any directory.

By default, patterns resolve against the rootDir set in your TS config file.

This can fix plugin errors when parsing files outside the current working directory (process.cwd()).

tsconfig

Type: String | Boolean
Default: true

When set to false, ignores any options specified in the config file. If set to a string that corresponds to a file path, the specified file will be used as config file.

typescript

Type: import('typescript')
Default: peer dependency

Overrides the TypeScript module used for transpilation.

typescript({
  typescript: require('some-fork-of-typescript')
});

tslib

Type: String
Default: peer dependency

Overrides the injected TypeScript helpers with a custom version.

typescript({
  tslib: require.resolve('some-fork-of-tslib')
});

transformers

Type: { [before | after | afterDeclarations]: TransformerFactory[] }
Default: undefined

Allows registration of TypeScript custom transformers at any of the supported stages:

• before: transformers will execute before the TypeScript's own transformers on raw TypeScript files
• after: transformers will execute after the TypeScript transformers on transpiled code
• afterDeclarations: transformers will execute after declaration file generation allowing to modify existing declaration files

Supported transformer factories:

• all built-in TypeScript custom transformer factories:

  • import('typescript').TransformerFactory annotated TransformerFactory bellow
  • import('typescript').CustomTransformerFactory annotated CustomTransformerFactory bellow

• ProgramTransformerFactory represents a transformer factory allowing the resulting transformer to grab a reference to the Program instance

  {
    type: 'program',
    factory: (program: Program) => TransformerFactory | CustomTransformerFactory
  }
  

• TypeCheckerTransformerFactory represents a transformer factory allowing the resulting transformer to grab a reference to the TypeChecker instance

  {
    type: 'typeChecker',
    factory: (typeChecker: TypeChecker) => TransformerFactory | CustomTransformerFactory
  }
  

typescript({
  transformers: {
    before: [
      {
        // Allow the transformer to get a Program reference in it's factory
        type: 'program',
        factory: (program) => {
          return ProgramRequiringTransformerFactory(program);
        }
      },
      {
        type: 'typeChecker',
        factory: (typeChecker) => {
          // Allow the transformer to get a TypeChecker reference in it's factory
          return TypeCheckerRequiringTransformerFactory(typeChecker);
        }
      }
    ],
    after: [
      // You can use normal transformers directly
      require('custom-transformer-based-on-Context')
    ],
    afterDeclarations: [
      // Or even define in place
      function fixDeclarationFactory(context) {
        return function fixDeclaration(source) {
          function visitor(node) {
            // Do real work here

            return ts.visitEachChild(node, visitor, context);
          }

          return ts.visitEachChild(source, visitor, context);
        };
      }
    ]
  }
});

cacheDir

Type: String
Default: .rollup.cache

When compiling with incremental or composite options the plugin will store compiled files in this folder. This allows the use of incremental compilation.

typescript({
  cacheDir: '.rollup.tscache'
});

noForceEmit

Type: Boolean
Default: false

Earlier version of @rollup/plugin-typescript required that the compilerOptions noEmit and emitDeclarationOnly both false to guarantee that source code was fed into the next plugin/output. This is no longer true. This option disables the plugin forcing the values of those options and instead defers to the values set in tsconfig.json.

noForceEmit can be very useful if you use with @rollup/plugin-babel and @babel/preset-typescript. Having @rollup/plugin-typescript only do typechecking / declarations with "emitDeclarationOnly": true while deferring to @rollup/plugin-babel for transpilation can dramatically reduce rollup build times for large projects.

Typescript compiler options

Some of Typescript's CompilerOptions affect how Rollup builds files.

noEmitOnError

Type: Boolean
Default: false

If a type error is detected, the Rollup build is aborted when this option is set to true.

files, include, exclude

Type: Array[...String]
Default: []

Declaration files are automatically included if they are listed in the files field in your tsconfig.json file. Source files in these fields are ignored as Rollup's configuration is used instead.

Ignored options

These compiler options are ignored by Rollup:

• noEmitHelpers, importHelpers: The tslib helper module always must be used.
• noEmit, emitDeclarationOnly: Typescript needs to emit code for the plugin to work with.
  • Note: While this was true for early iterations of @rollup/plugin-typescript, it is no longer. To override this behavior, and defer to tsconfig.json for these options, see the noForceEmit option
• noResolve: Preventing Typescript from resolving code may break compilation

Importing CommonJS

Though it is not recommended, it is possible to configure this plugin to handle imports of CommonJS files from TypeScript. For this, you need to specify CommonJS as the module format and add @rollup/plugin-commonjs to transpile the CommonJS output generated by TypeScript to ES Modules so that rollup can process it.

// rollup.config.js
import typescript from '@rollup/plugin-typescript';
import commonjs from '@rollup/plugin-commonjs';

export default {
  input: './main.ts',
  plugins: [
    typescript({ compilerOptions: { module: 'CommonJS' } }),
    commonjs({ extensions: ['.js', '.ts'] }) // the ".ts" extension is required
  ]
};

Note that this will often result in less optimal output.

Preserving JSX output

Whenever choosing to preserve JSX output to be further consumed by another transform step via tsconfig compilerOptions by setting jsx: 'preserve' or overriding options, please bear in mind that, by itself, this plugin won't be able to preserve JSX output, usually failing with:

[!] Error: Unexpected token (Note that you need plugins to import files that are not JavaScript)
file.tsx (1:15)
1: export default <span>Foobar</span>
                  ^

To prevent that, make sure to use the acorn plugin, namely acorn-jsx, which will make Rollup's parser acorn handle JSX tokens. (See https://rollupjs.org/guide/en/#acorninjectplugins)

After adding acorn-jsx plugin, your Rollup config would look like the following, correctly preserving your JSX output.

import jsx from 'acorn-jsx';
import typescript from '@rollup/plugin-typescript';

export default {
  // … other options …
  acornInjectPlugins: [jsx()],
  plugins: [typescript({ compilerOptions: { jsx: 'preserve' } })]
};

Faster compiling

Previous versions of this plugin used Typescript's transpileModule API, which is faster but does not perform typechecking and does not support cross-file features like const enums and emit-less types. If you want this behaviour, you can use @rollup/plugin-sucrase instead.

Declaration Output With output.file

When instructing Rollup to output a specific file name via the output.file Rollup configuration, and TypeScript to output declaration files, users may encounter a situation where the declarations are nested improperly. And additionally when attempting to fix the improper nesting via use of outDir or declarationDir result in further TypeScript errors.

Consider the following rollup.config.js file:

import typescript from '@rollup/plugin-typescript';

export default {
  input: 'src/index.ts',
  output: {
    file: 'dist/index.mjs'
  },
  plugins: [typescript()]
};

And accompanying tsconfig.json file:

{
  "include": ["*"],
  "compilerOptions": {
    "outDir": "dist",
    "declaration": true
  }
}

This setup will produce dist/index.mjs and dist/src/index.d.ts. To correctly place the declaration file, add an exclude setting in tsconfig and modify the declarationDir setting in compilerOptions to resemble:

{
  "include": ["*"],
  "exclude": ["dist"],
  "compilerOptions": {
    "outDir": "dist",
    "declaration": true,
    "declarationDir": "."
  }
}

This will result in the correct output of dist/index.mjs and dist/index.d.ts.

For reference, please see the workaround this section is based on here

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CONTRIBUTING

LICENSE (MIT)