A simple way to use Web Worker with React-Create-APP - No eject needed

#react #worker #typescript #javascript

The problem of using Web Worker with an app that start with create-react-app is that:

create-react-app hide its webpack config from user to modify, if not ejected.
You need to modify webpack config in order to emit worker file.
If ejected, the webpack.config is overwhelming and hard to modify.
worker-loader is not very typescript-friendly.

A Solution

We can generator worker.js by running another webpack thread that only take care worker files. Here are what we need to do:

If you haven't install webpack-cli, you need to install it.

I'm using typescript, so let's install the ts-loader.

Then, add a webpack.config.js file at project root like this:

const path = require('path');
const webpack = require('webpack');

const src = path.resolve(__dirname, './src');
const build = path.resolve(__dirname, './public'); // output worker.js to public folder


const tsLoader = {
  loader: 'ts-loader',
  options: { compilerOptions: { module: 'esnext', noEmit: false } }
}


module.exports = {
  mode: 'none',
  target: "webworker", //Importan! Use webworker target
  entry: './src/worker.ts',
  output: {
    filename: 'worker.js',
    path: build
  },
  resolve: {
    modules: ["node_modules", src],
    extensions: [".js", ".json", ".jsx", ".ts", ".tsx"],
  },

  plugins: [
    new webpack.HotModuleReplacementPlugin(),
    new webpack.DefinePlugin({ 'process.env.NODE_ENV': JSON.stringify('development') })
  ],
  module: {
    rules: [
      {
        test: /\.ts?$/,
        use: [tsLoader]
      },

    ]
  }
};

Note, we need to change the following config:

Change output to ./public folder so react-scripts can use it.
The target needs to be webworker.
Add compilerOptions: {..., noEmit: false, ...} to ts-loader options. This will overwrite the noEmit:true in the tsconfig.json that created by create-react-app.