service-worker-plugin/index.js

Service Worker Plugin ========================= A webpack plugin for generating dynamic service worker files and a runtime helper.

const fs = require('fs');
const path = require('path');
const mkdirp = require('mkdirp');
const generateServiceWorkers = require('../generate-service-worker');
const generateRuntime = require('./utils/generateRuntime');
const mapPrecacheAssets = require('./utils/mapPrecacheAssets');

const runtimePath = path.resolve(__dirname, 'runtime.js');

function ProgressiveWebappPlugin(baseConfig, experimentConfigs) {
  this.baseConfig = baseConfig || {};
  this.experimentConfigs = experimentConfigs || {};
}

ProgressiveWebappPlugin.prototype.apply = function (compiler) {
  const publicPath = this.baseConfig.publicPath || compiler.options.output.publicPath;
  const writePath = this.baseConfig.writePath || compiler.options.output.path;
  mkdirp.sync(writePath);

  // Write the runtime file
  const workerKeys = ['main'].concat(Object.keys(this.experimentConfigs));
  const generatedRuntime = generateRuntime(workerKeys, this.baseConfig.runtimePath || publicPath);
  fs.writeFileSync(runtimePath, generatedRuntime);

  // Generate service workers
  const emit = (compilation, callback) => {
    const assets = compilation.assets;
    // Update configs with matched precache asset paths
    const baseConfigWithPrecache = mapPrecacheAssets(assets, this.baseConfig, publicPath);
    const expConfigsWithPrecache = Object.keys(this.experimentConfigs).reduce((result, key) => {
      // eslint-disable-next-line no-param-reassign
      result[key] = mapPrecacheAssets(assets, this.experimentConfigs[key], publicPath);
      return result;
    }, {});
    const serviceWorkers = generateServiceWorkers(baseConfigWithPrecache, expConfigsWithPrecache);

    // Write files to file system
    Object.keys(serviceWorkers).forEach(key => {
      const fullWritePath = path.join(writePath, `sw-${key}.js`);
      // Write to file system
      fs.writeFileSync(fullWritePath, serviceWorkers[key]);
      // Add to compilation assets
      // eslint-disable-next-line no-param-reassign
      assets[fullWritePath] = {
        source: function () {
          return serviceWorkers[key];
        },
        size: function () {
          return serviceWorkers[key].length;
        }
      };
    });

    callback();
  };
  if (compiler.hooks) {
    const plugin = { name: 'ServiceWorkerPlugin' };
    compiler.hooks.emit.tap(plugin, emit);
  } else {
    compiler.plugin('emit', emit);
  }
};

module.exports = ProgressiveWebappPlugin;