TypeScript with Laravel Mix

Since writing this post, TypeScript has become officially supported in Laravel Mix (version 0.12 and up). There's still some informative stuff in here if you're new to TypeScript, but use the official method if you're on a newer version of Mix!

In a recent Spatie project we decided to give TypeScript a shot for the business critical part of a new application. TypeScript provides static analysis to reduce the chance of introducing bugs, to have self-documenting code, and to improve our tooling (autocompletion!)

We've been happily using Laravel Mix since it's release with Laravel 5.4. Luckily, extending Mix isn't too hard with some webpack knowledge. One of my favorite features of webpack is the ability to import a module in your application without caring about what kind of file it actually is. As long as you've configured an appropriate loader, you could import anything from a plain old JavaScript file to an animated gif. This means that if we want to support TypeScript with Laravel Mix, we don't need to change any configuration, we only need to add the ability to bundle TypeScript files.

I've created an example repository on GitHub. The readme contains a concise step-by-step checklist for adding TypeScript support to Laravel Mix if you prefer a quick reference over a more detailed guide.

This post assumes you know the basic concepts Laravel Mix, you know the basic concepts of webpack, and that you're using a somewhat standard Laravel 5.4 installation.

Adding TypeScript support is pretty straight forward and is done in three steps: install the necessary dependencies, configure TypeScript, and finally configure Laravel Mix.

1) Install The Necessary Dependencies

Let's start with installing the necessary dependencies that Laravel & Mix don't provide out of the box:

yarn add ts-loader typescript --dev

typescript is, well, the TypeScript compiler itself, doesn't really warrant an explanation. ts-loader is the official webpack loader for TypeScript. Webpack uses loaders to determine how it should parse a module that you include in your JavaScript. The --dev flag ensures that the two new dependencies are stored in our project's devDependencies.

2) Configure TypeScript

TypeScript requires a configuration file to work properly. We can create one using node_modules/.bin/tsc --init. (no need for the full path if you have a global TypeScript installation) We're not going to dive into the details of configuring TypeScript since that's outside of the scope of this post, the default configuration that appears in the newly created tsconfig.json file will do.

{
  "compilerOptions": {
    "module": "commonjs",
    "target": "es5",
    "noImplicitAny": false,
    "sourceMap": false
  }
}

We'll add one more line though. Webpack doesn't need this, but by specifying where our source files are, our editor can provide better type validation & autocompletion. Since we're in a default Laravel installation, our TypeScript files will be located in resources/assets/js.

{
  "compilerOptions": {
    "module": "commonjs",
    "target": "es5",
    "noImplicitAny": false,
    "sourceMap": false
  },
  "include": ["resources/assets/js/**/*"]
}

3) Configure Laravel Mix

Since we're adding a new loader to webpack, we need to modify Mix' webpack configuration. Luckily there's a public method for that so we don't need to do anything hacky: webpackConfig, which can be chained to the rest of our Mix configuration in our webpack.mix.js file.

Our loader should:

• Only apply to TypeScript files (.ts and .tsx)
• Transform TypeScript files to JavaScript with ts-loader
• Not care about anything that comes from the node_modules folder, we only care about managing our own application code

This boils down to the following loader configuration:

const { mix } = require("laravel-mix");
 
mix
  .js("resources/assets/js/app.js", "public/js")
  .sass("resources/assets/sass/app.scss", "public/css")
  .webpackConfig({
    module: {
      rules: [
        {
          test: /\.tsx?$/,
          loader: "ts-loader",
          exclude: /node_modules/
        }
      ]
    }
  });

We also don't want to specify file extension whenever we import or require a TypeScript file, so we'll need to tell webpack to look for .ts and .tsx files when it has to make a guess. Mix already supports a list of extensions, to ensure we're not breaking anything, we'll copy the original array (which is declared in the laravel-mix package) and append our new extensions. This all happens in resolve.extensions.

const { mix } = require("laravel-mix");
 
mix
  .js("resources/assets/js/app.js", "public/js")
  .sass("resources/assets/sass/app.scss", "public/css")
  .webpackConfig({
    module: {
      rules: [
        {
          test: /\.tsx?$/,
          loader: "ts-loader",
          exclude: /node_modules/
        }
      ]
    },
    resolve: {
      extensions: ["*", ".js", ".jsx", ".vue", ".ts", ".tsx"]
    }
  });

4) Write Some TypeScript!

Pretty important, let's see if everything works! We'll start by creating a dead simple TypeScript file, resources/assets/js/hello-world.ts

export function helloWorld(): string {
  return "Hello world!";
}

We can require the hello-world.ts file in our app.js file without needing to specify the extension, since we added it to webpack's resolve.extensions option.

const helloWorld = require("./hello-world").helloWorld();
 
console.log(helloWorld);

When we open our browser, Hello world! appears in the console. Success!

Bonus Step: Configure Mix to Use TypeScript in Vue Components

If we want TypeScript to compile script contents in Vue components too, we need to tell ts-loader to deal with .vue files too. There's a special option for that: appendTsSuffixTo. Here's what our new loader configuration looks like:

{
    test: /\.tsx?$/,
    loader: 'ts-loader',
    options: { appendTsSuffixTo: [/\.vue$/] },
    exclude: /node_modules/,
}

Now we can use TypeScript in our components, as long as we specify the language in the script tags.

<template>
  <div></div>
</template>
 
<script lang="ts">
  export default {
    mounted(): void {
      console.log("Component mounted.");
    }
  };
</script>

That's it! I've created an example repository on GitHub. The readme contains a concise step-by-step checklist for adding TypeScript support to Laravel Mix if you prefer a quick reference over a more detailed guide.