How to Use the Fork TS Checker Webpack Plugin

Setting Up Fork TS Checker in Your Project

To start using Fork TS Checker, you need to install it along with TypeScript if you haven't done so already. Run the following command in your terminal:

npm install --save-dev fork-ts-checker-webpack-plugin typescript

Next, you will need to add the plugin to your Webpack configuration file. Open your webpack.config.js file and include the following lines:

const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');

module.exports = {
    // other configuration options...
    plugins: [
        new ForkTsCheckerWebpackPlugin(),
    ],
};

This setup allows the plugin to start monitoring your TypeScript files for errors during the build process.

Related Article: How to Use Webpack Manifest Plugin

Configuring Options

The Fork TS Checker Webpack Plugin comes with several options that can be configured to suit your project's needs. Here are some commonly used options:

- async: Determines whether to run type checking asynchronously. The default is true.

- typescript: An object that can specify the path to the TypeScript configuration file.

- eslint: An object to configure ESLint integration.

- reportFiles: Defines which files to check for type errors.

Here’s an example of how to configure these options in your webpack.config.js:

const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');

module.exports = {
    // other configuration options...
    plugins: [
        new ForkTsCheckerWebpackPlugin({
            async: true,
            typescript: {
                configFile: './tsconfig.json',
            },
            reportFiles: ['src/**/*.{ts,tsx}'],
        }),
    ],
};

This setup customizes Fork TS Checker to check all TypeScript files in the src directory while looking at the specified tsconfig.json for TypeScript settings.

Type Checking

Type checking with Fork TS Checker is performed in a separate worker process, allowing the main Webpack build to continue running without waiting for type errors to be resolved. This means that you can keep working on your project without experiencing slowdowns.

When you run your Webpack build, Fork TS Checker will automatically check your TypeScript files. Errors will be shown in the console, and if you have integrated ESLint, those errors will also be displayed.

To see type checking in action, simply run your Webpack build:

npx webpack --config webpack.config.js

As errors are found, they will be displayed in the terminal output.

Error Handling

Fork TS Checker provides a robust error handling mechanism. When type errors occur, they are reported directly in the console. You can customize how errors are displayed by configuring the formatter option in Fork TS Checker. For example, you can use typescript's built-in formatter or implement your own.

Here’s an example of how to set up a custom formatter:

const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');

module.exports = {
    // other configuration options...
    plugins: [
        new ForkTsCheckerWebpackPlugin({
            formatter: (messages) => {
                messages.forEach(message => {
                    console.log(`[TypeScript Error] ${message}`);
                });
            },
        }),
    ],
};

This will log each TypeScript error with a custom message prefix in the terminal.

Related Article: How to Set Up Webpack Proxy for Development

Improving Build Performance with Fork TS Checker

To improve the performance of your builds, Fork TS Checker runs type checks in a separate process. This means that your main Webpack build does not have to wait for type checking to complete. You can further enhance performance by adjusting certain options.

Setting the async option to true allows type checking to run in parallel with the build process. Additionally, limiting the files checked by using the reportFiles option can also lead to faster builds.

Here’s an example that demonstrates how to limit the types of files checked:

const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');

module.exports = {
    // other configuration options...
    plugins: [
        new ForkTsCheckerWebpackPlugin({
            async: true,
            reportFiles: ['src/<strong>/*.{ts,tsx}', '!src/</strong>/*.spec.ts'],
        }),
    ],
};

In this case, all TypeScript and TSX files are checked except for test files, which can reduce the time spent on type checking during development.

Fork TS Checker and ESLint Integration

Integrating ESLint with Fork TS Checker allows you to catch both TypeScript and linting errors in a single workflow. To set this up, ensure you have ESLint and the necessary TypeScript ESLint packages installed:

npm install --save-dev eslint eslint-plugin-typescript

In your Webpack configuration, you can enable ESLint integration as follows:

const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');

module.exports = {
    // other configuration options...
    plugins: [
        new ForkTsCheckerWebpackPlugin({
            eslint: {
                files: './src/**/*.{ts,tsx}',
            },
        }),
    ],
};

With this configuration, Fork TS Checker will run ESLint checks on the specified files along with TypeScript checks.

Module Resolution

Fork TS Checker uses the same module resolution strategy as TypeScript. By default, it will look for a tsconfig.json file in your project's root directory. This means that any custom paths or settings you've defined in your tsconfig.json will be honored during type checking.

If you want to specify a different configuration file for Fork TS Checker, you can do so using the typescript option:

const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');

module.exports = {
    // other configuration options...
    plugins: [
        new ForkTsCheckerWebpackPlugin({
            typescript: {
                configFile: './custom-tsconfig.json',
            },
        }),
    ],
};

This will direct Fork TS Checker to use the specified custom-tsconfig.json for module resolution.

Hot Module Replacement

Hot Module Replacement (HMR) is a feature that allows you to update modules in a running application without a full reload. Fork TS Checker works seamlessly with HMR, enabling live reloading while providing type checking in the background.

To enable HMR, you need to configure your Webpack dev server. Here's an example configuration that incorporates HMR along with Fork TS Checker:

const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');

module.exports = {
    // other configuration options...
    devServer: {
        hot: true,
    },
    plugins: [
        new ForkTsCheckerWebpackPlugin(),
    ],
};

With this setup, whenever you make changes to your TypeScript files, the application will update without a full reload, and Fork TS Checker will continue to check for any type errors.

Related Article: How to Configure DevServer Proxy in Webpack

Compatibility of Fork TS Checker with Webpack Versions

Fork TS Checker is compatible with various versions of Webpack, including Webpack 4 and 5. It takes advantage of Webpack’s plugin architecture, ensuring that it works seamlessly with either version.

To ensure compatibility, always check the plugin's documentation for any specific requirements related to the Webpack version you are using. Keeping your packages up to date is recommended to avoid any potential issues.

Using Fork TS Checker in a Multi-Compiler Setup

When working on a project with multiple entry points or configurations, Fork TS Checker can still be utilized effectively. You can set up multiple instances of Fork TS Checker, one for each compiler configuration. This is particularly useful in monorepo setups or when using multiple applications.

Here’s an example of how to configure Fork TS Checker for multiple compilers:

const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');

module.exports = [
    {
        // Configuration for the first compiler
        plugins: [
            new ForkTsCheckerWebpackPlugin(),
        ],
    },
    {
        // Configuration for the second compiler
        plugins: [
            new ForkTsCheckerWebpackPlugin(),
        ],
    },
];

Each configuration will handle type checking independently, allowing for a modular approach to managing multiple projects.

Comparing Fork TS Checker to Other TypeScript Plugins

When comparing Fork TS Checker to other TypeScript plugins like ts-loader, it is important to note the primary difference in how they handle type checking. ts-loader performs type checking synchronously, which can slow down the build process, especially in larger projects. Fork TS Checker, on the other hand, runs type checks in a separate process, allowing for a more responsive development experience.

Another alternative is babel-loader, which can transpile TypeScript but does not perform type checking. Developers often combine babel-loader with Fork TS Checker to achieve both speed and type safety.

Additional Resources