Build 10x products in minutes by chatting with AI - beyond just a prototype.
Topics
Rollup is a module bundler for JavaScript which compiles small pieces of code into something larger and more complex, such as a library or application. TypeScript is a typed superset of JavaScript that compiles to plain JavaScript.
To bridge the gap between these two, the rollup plugin typescript2 is used. This plugin leverages TypeScript to transpile TypeScript code to JavaScript, allowing developers to use TypeScript's static typing system within a Rollup build process.
The rollup plugin typescript2 is an essential tool for developers who want to ensure their TypeScript code is bundled correctly. It not only transpiles the code but also respects TypeScript's compiler options, and generates declaration files to provide types for use in other TypeScript projects.
1import typescript from 'rollup-plugin-typescript2'; 2 3export default { 4 input: './src/main.ts', 5 output: { 6 file: './dist/bundle.js', 7 format: 'cjs' 8 }, 9 plugins: [typescript()] 10};
In the above rollup config, we import the rollup plugin typescript2 and use it within the plugins array. This setup is the starting point for integrating TypeScript into your Rollup build.
To use TypeScript with Rollup, you need to set up a rollup configuration file that includes the rollup plugin typescript2. This plugin will handle the TypeScript compilation and ensure that the generated rollup bundle is in pure JavaScript. Here's a basic setup:
1import typescript from 'rollup-plugin-typescript2'; 2 3export default { 4 input: 'src/index.ts', 5 output: [ 6 { file: 'dist/my-library.js', format: 'umd', name: 'MyLibrary' }, 7 { file: 'dist/my-library.esm.js', format: 'es' } 8 ], 9 plugins: [typescript({ useTsconfigDeclarationDir: true })] 10};
In this configuration, we specify the input ts files, the output js files, and include the rollup plugin typescript2 in the plugin list. The useTsconfigDeclarationDir option tells the plugin to use the declaration directory specified in the tsconfig.json file.
The rollup plugin typescript2 offers several features that make it a preferred choice over alternative typescript implementations. It provides error reporting that can be customized through plugin options, and it can generate declaration files and declaration maps. Additionally, it can work with type only imports and file extensions like tsx files.
One of the key benefits of using rollup plugin typescript2 is its ability to chain generate typescript declaration files, which is crucial for library authors who want to publish their types along with their JavaScript code.
1// Example of chaining plugins to generate TypeScript declaration files 2import typescript from 'rollup-plugin-typescript2'; 3import dts from 'rollup-plugin-dts'; 4 5const config = [ 6 { 7 input: './src/index.ts', 8 output: [{ file: 'dist/index.js', format: 'cjs' }], 9 plugins: [typescript()] 10 }, 11 { 12 input: './src/index.ts', 13 output: [{ file: 'dist/index.d.ts', format: 'es' }], 14 plugins: [dts()] 15 } 16]; 17 18export default config;
In the above example, we use composing rollup plugins to first transpile TypeScript code to JavaScript and then generate the corresponding declaration files.
Configuring the rollup plugin typescript2 involves setting various plugin options in the rollup configuration file. These options control how the plugin performs, including where to place declaration files, how to handle compiler errors, and whether to use rollup controls emit to determine which files should be emitted.
1// Example of configuring plugin options 2import typescript from 'rollup-plugin-typescript2'; 3 4export default { 5 // ... 6 plugins: [ 7 typescript({ 8 tsconfigOverride: { compilerOptions: { declaration: true } }, 9 objectHashIgnoreUnknowns: true 10 }) 11 ] 12};
In this configuration, we override the tsconfig.json settings to ensure that declaration files are generated. The objectHashIgnoreUnknowns option helps the plugin to ignore unknown properties when generating the cache key, which can be useful when dealing with unknown object type errors.
Rollup plugins are modular tools that can be composed together to enhance and customize the build process. The rollup plugin list can include a variety of plugins for different tasks, such as minifying code, loading import files from node_modules, or even converting import commonjs modules to ES6.
When composing rollup plugins, it's important to consider the order in which they are applied, as some plugins may depend on the transformations performed by others. Here's an example of a rollup config with multiple plugins:
1import typescript from 'rollup-plugin-typescript2'; 2import commonjs from '@rollup/plugin-commonjs'; 3import resolve from '@rollup/plugin-node-resolve'; 4 5export default { 6 // ... 7 plugins: [ 8 resolve(), 9 commonjs(), 10 typescript() 11 ] 12};
In this setup, the resolve plugin helps Rollup to find import files in the node_modules directory, the commonjs plugin converts CommonJS modules to ES6, and the rollup plugin typescript2 handles TypeScript transpilation.
The rollup plugin DTS is a plugin specifically designed to generate TypeScript declaration files. These files are essential for TypeScript projects as they define the types and interfaces of the export default and named exports in your code, allowing other TypeScript projects to use your library with type safety.
The plugin can also create declaration maps, which map the generated declaration files back to the original source, making it easier to navigate to the source code from the types.
1import dts from 'rollup-plugin-dts'; 2 3export default { 4 input: 'src/index.ts', 5 output: [{ file: 'dist/index.d.ts', format: 'es' }], 6 plugins: [dts()] 7};
In the above example, the rollup plugin DTS takes the TypeScript source file and generates a corresponding .d.ts file. This ambient types effectively hides the implementation details while providing a stable interface for consumers.
The rollup plugin node resolve is another essential tool that simplifies the process of resolving import files within a Rollup bundle. It allows you to use import statements that reference node modules as if they were ES modules, providing a stable interface for dependencies.
This plugin is particularly useful when dealing with import commonjs modules, as it can resolve them and allow Rollup to include them in the bundle.
1import resolve from '@rollup/plugin-node-resolve'; 2 3export default { 4 // ... 5 plugins: [ 6 resolve({ 7 mainFields: ['module', 'main'], 8 extensions: ['.js', '.ts'] 9 }) 10 ] 11};
In the configuration above, the resolve plugin is configured to look for the module and main fields in the package.json of the imported module, and it includes both .js and .ts in the list of file extensions to resolve.
When using TypeScript with Rollup, rollup controls emit determines which files are included in the final bundle. The rollup plugin typescript2 uses the TypeScript compiler to transpile ts files to js files, and it can be configured to handle javascript compilation in various ways.
The plugin also interfaces with the TypeScript compiler, using compiler interfaces to provide detailed control over the compilation process. This includes handling semantic diagnostic messages and compiler errors.
1import typescript from 'rollup-plugin-typescript2'; 2 3export default { 4 // ... 5 plugins: [ 6 typescript({ 7 check: false, // Disable semantic checks 8 clean: true // Clear the .rts2_cache directory between builds 9 }) 10 ] 11};
In this snippet, the check option is set to false to disable semantic checks, which can speed up the build process if you are handling type checking elsewhere. The clean option ensures that the existing cache is cleared, which can prevent issues related to stale files.
The rollup plugin typescript2 provides options to handle semantic diagnostic messages and compiler errors. The abortonerror plugin option can be set to false to prevent Rollup from aborting the build when TypeScript errors are detected. This can be useful during development when you want to see the output even if there are type errors.
1import typescript from 'rollup-plugin-typescript2'; 2 3export default { 4 // ... 5 plugins: [ 6 typescript({ 7 abortOnError: false 8 }) 9 ] 10};
In the configuration above, setting abortOnError to false allows the build to complete, but it will still log the compiler errors to the console. This way, developers can address the errors at their convenience without interrupting the workflow.
To optimize the development experience, Rollup provides a watch mode that automatically rebuilds your project when it detects changes to the source files. When combined with rollup plugin typescript2, watch mode can significantly speed up the development cycle by using an existing cache to avoid unnecessary recompilation of unchanged files.
The cache key is an important aspect of this caching mechanism. It ensures that only the changed files are recompiled, which can save a lot of time during development.
1// Enabling watch mode in Rollup config 2export default { 3 // ... 4 watch: { 5 include: 'src/**', 6 clearScreen: false 7 }, 8 plugins: [ 9 // ... other plugins 10 ] 11};
In the Rollup configuration above, the watch property is set to include all files in the src directory. The clearScreen option is set to false to keep the console output visible between rebuilds.
The rollup plugin typescript2 is capable of handling not only ts files but also tsx files. This is particularly useful for projects that use JSX syntax, such as those built with React. To work with these different file types, you may need to change file extensions in your TypeScript configuration to ensure that all relevant files are included in the compilation process.
1// Handling different file types in tsconfig.json 2{ 3 "compilerOptions": { 4 "jsx": "react", 5 "allowJs": true, 6 "extensions": [".ts", ".tsx"] 7 }, 8 "include": ["src/**/*"] 9}
In the tsconfig.json snippet above, the jsx option is set to react to support JSX syntax, and the extensions option includes both .ts and .tsx files.
While rollup plugin typescript2 primarily handles TypeScript transpilation, you may also want to integrate Babel plugins for additional code transformations. Babel can be used alongside TypeScript to transpile newer JavaScript features that TypeScript may not support, or to apply specific transformations such as stripping out type only imports.
1import typescript from 'rollup-plugin-typescript2'; 2import babel from '@rollup/plugin-babel'; 3 4export default { 5 // ... 6 plugins: [ 7 typescript(), 8 babel({ 9 extensions: ['.ts', '.tsx'], 10 babelHelpers: 'bundled' 11 }) 12 ] 13};
In the Rollup configuration above, the babel plugin is included after the rollup plugin typescript2. It's configured to handle .ts and .tsx files and to bundle the Babel helpers with the final output.
Advanced Rollup configurations may involve fine-tuning how rollup controls the build output and how a rollup plugin inherits options from another. For instance, you might want to update plugin's include filter or use the objectHashIgnoreUnknowns option to ignore changes in the build environment that do not affect the output.
1import typescript from 'rollup-plugin-typescript2'; 2 3export default { 4 // ... 5 plugins: [ 6 typescript({ 7 include: ['src/**/*.ts', 'src/**/*.tsx'], 8 objectHashIgnoreUnknowns: true 9 }) 10 ] 11};
In this configuration, the include option is updated to specify which files the rollup plugin typescript2 should process. The objectHashIgnoreUnknowns option helps to maintain a consistent cache even if some external factors change.
During the development process, you might encounter various issues such as a semantic error, an unexpected token, or changes in compiler interfaces. These can often be resolved by adjusting your rollup plugin typescript2 configuration or by ensuring that your TypeScript version is compatible with the plugin.
A common issue is the unexpected token error, which can occur when TypeScript encounters syntax it doesn't recognize. This can be due to using newer JavaScript features that haven't been configured in your TypeScript or Babel setup.
1// Example TypeScript configuration to handle JSX syntax 2{ 3 "compilerOptions": { 4 "jsx": "preserve", 5 "target": "esnext" 6 } 7}
In the tsconfig.json snippet above, setting the jsx option to preserve tells TypeScript to leave JSX syntax intact for Babel to handle, which can prevent unexpected token errors related to JSX.
While rollup plugin typescript2 is a popular choice for TypeScript integration with Rollup, there are alternatives like rollup plugin swc and rollup plugin esbuild. These plugins offer faster build times by leveraging Rust and Go, respectively, for the compilation process.
1import swc from 'rollup-plugin-swc'; 2import esbuild from 'rollup-plugin-esbuild'; 3 4export default { 5 // ... 6 plugins: [ 7 swc({ 8 // SWC options 9 }), 10 esbuild({ 11 // ESBuild options 12 }) 13 ] 14};
In the configuration above, both rollup plugin swc and rollup plugin esbuild are included as alternatives to rollup plugin typescript2. These plugins can be particularly useful for large projects where build performance is a critical factor.
When working with TypeScript modules in Rollup, it's important to follow best practices to ensure compatibility and maintainability. This includes correctly configuring your typescript module settings in tsconfig.json and understanding how to import typescript modules in a way that Rollup can process them.
1// Example of TypeScript module configuration 2{ 3 "compilerOptions": { 4 "module": "esnext", 5 "moduleResolution": "node" 6 } 7}
In the tsconfig.json snippet above, the module option is set to esnext to use the latest module syntax, and moduleResolution is set to node for compatibility with the Node.js module resolution algorithm.
In conclusion, rollup plugin typescript2 is a powerful tool that can streamline your TypeScript workflow within a Rollup build. By placing the plugin in your project directory and configuring it properly, you can ensure that your TypeScript code is compiled efficiently and effectively.
Remember to keep your rollup configuration scalable and maintainable, and consider using other rollup plugins to enhance your build process. With the right setup, you can enjoy the benefits of TypeScript's type safety and Rollup's efficient bundling in your projects.
1// Final Rollup configuration example 2import typescript from 'rollup-plugin-typescript2'; 3 4export default { 5 input: 'src/main.ts', 6 output: { 7 dir: 'dist', 8 format: 'es' 9 }, 10 plugins: [typescript()], 11 // Additional Rollup settings for scalability 12};
In the final Rollup configuration example above, we have a simple yet scalable setup that includes rollup plugin typescript2. This setup can serve as a foundation for further customization and optimization as your project grows.
