Hello Preact Modules

In a previous note I created a Preact example with minimal configuration. In that example I added Preact using script tag instead of using ES6 modules. To make this work I need to install webpack and babel-loader.

Webpack allow us to convert the preact package into a preact module. While in the other hand babel-loader is a webpack loader that allow us to convert ES6 code into ES5.

Following the previous example, I am going to use the same HTML file, but removing the Preact script tag, so it looks like the code below:

<!doctype html>
<html>
  <head>
    <title>Hello Preact</title>
  </head>
  <body>
    <div id="root"></div>
    <script src="bundle.js"></script>
  </body>
</html>

Now I'm replacing the following line from app.js to use import.

From:

const { h, render, Component } = window.preact;

To:

import { h, render, Component } from 'preact';

Webpack & Babel Loader

I need to install webpack, webpack-cli, and babel-loader using npm.

npm install --save-dev babel-loader webpack webpack-cli

I am going to install webpack-cli to execute webpack from the command line.

Webpack Configuration

I need to create a new file for the webpack configuration named webpack.config.js. This file will tells webpack what's the input and output file, and to use the babel-loader to convert the ES6 features.

In the previous example this was done using the babel command, now webpack will take care of all this.

module.exports = {
    entry: './app.js',
    output: {
        path: __dirname,
        filename: 'bundle.js'
    },
    module: {
        rules: [
            {
              test: /\.js$/,
                loader: 'babel-loader'
            }
        ]
    }
}

Webpack is ready to be used to convert app.js into bundle.js, allowing us to use import as well.

Build Script

We are now replacing the build script from package.json to use webpack instead of babel.

From:

"scripts": {
  "build": "babel app.js -o bundle.js",
  "test": "echo \"Error: no test specified\" && exit 1"
},

To:

"scripts": {
  "build": "webpack",
  "test": "echo \"Error: no test specified\" && exit 1"
},

Run the build command, and access index.html to see the result.

$ npm run build

See final code here: WellingGuzman/hello-preact.

Index