Precache Files with Webpack

This page explains how to use the workbox-webpack-plugin node module to generate the list of files to precache and add it to your service worker.

Install `workbox-webpack-plugin`

Start by installing `workbox-webpack-plugin` from npm.

npm install workbox-webpack-plugin --save-dev

Setup your Webpack Config

To add the manifest to your service worker file you'll need to add the plugin to your webpack.config.js file like so:

// Inside of webpack.config.js:
const WorkboxPlugin = require('workbox-webpack-plugin');

module.exports = {
  // Other webpack config...

  plugins: [
    // Other plugins...

    new WorkboxPlugin.InjectManifest({
      swSrc: './src/sw.js',

If you look at the output of your service worker file you'll see an extra file is added as an importScripts() call. It'll be named precache-manifest.<revision>.js. This file will contain the list of files to precache and it will expose the list as the variable self.__precacheManifest.

Precache Files

The final step is to tell Workbox to precache the files, which you can do by adding the following code to your service worker.

workbox.precaching.precacheAndRoute(self.__precacheManifest || []);

This will precache any of the files from the Webpack plugin.

Further Reading

The workbox.precaching API provides some options for configuration should you need to customize any of the default behaviors. Learn more on the workbox.precaching page.