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Switching from ts-loader to babel-loader

Why to switch?

  • Babel’s ecosystem has evolved for supporting typescript. Now its no more just a javascript transpiler for various targets.
  • Babel is comparitively faster than tsc. Because it ignores types and works as if it is a javascript code.
  • Downside of this is that it ignores type-checking.
  • Often people chain ts-loader and babel-loader thus unnecessary increasing the build time.
  • ts-loader use to convert typescript to javascript and then babel-loader for converting that javascript to target browsers friendly javascript as per our requirement.
  • Better tree-shaking resulting in smaller bundle size.

What are we doing?

  1. We will convert typescript directly to target environment javascript bundle using babel-loader and its supporting presets and plugins.
  2. For the missing type-checking we will use eslint and tsc with —noEmit option, so that it does type-checking but do not output any files because babel is already doing that.

Alright, how to do it?

  1. npm install -D babel-loader @babel/core @babel/preset-react @babel/preset-typescript
  2. Change your webpack configuration.
module.exports = {
    module: {
      rules: [
        {
          test: /\.(ts|tsx)$/,
          loader: 'ts-loader',
          exclude: /node_modules/,
        }
      ]
    },
  ...
}
module.exports = {
    module: {
      rules: [
          {
            test: /\.(ts|tsx)$/,
            loader: 'babel-loader',
            options: {
              // without additional settings, this will reference .babelrc
              presets: ['@babel/preset-react', '@babel/preset-typescript']
            },
            exclude: /node_modules/,
          }
        ]
    },
  ...
}
  1. For detailed babel configuration and various presets and plugins you may add a .babelrc file.
  2. For specifying target environments you want your javascript to be transpiled for, you can add @babel/preset-env.

And that’s it.

For the missing type-checking we can add a npm script in package.json say "check-types": "tsc --project src/tsconfig.json --noEmit.

Hope you enjoyed reading this. Feel free to drop feedback in comments.

- Ayush 🙂