ServiceWorkerPlugin.js

'use strict';
const SingleEntryPlugin = require('webpack/lib/SingleEntryPlugin');
const webpack = require('webpack');
const CHILD_COMPILER_NAME = 'service-worker-plugin';

class ServiceWorkerPlugin {

  constructor(options) {
    this.options = options;
  }

  apply(compiler) {

    compiler.plugin('emit', (compilation, callback) => {
      const stats = compilation.getStats().toJson();
      const child = compilation.createChildCompiler(CHILD_COMPILER_NAME, {
        filename: this.options.output,
      });

      child.apply(
        new SingleEntryPlugin(compiler.context, this.options.entry, this.options.output)
      );

      child.apply(
        new webpack.DefinePlugin({
          SHA: JSON.stringify(process.env.CI_COMMIT || 'unreleased'),
          ASSETS: JSON.stringify(stats.assets.map((asset) => `/m/public/${asset.name}`).filter((name) =>  !name.endsWith('.map'))),
        })
      );


      child.runAsChild((err) => {
        if (err) callback(err);
        callback();
      });
    });
  }
}

module.exports = ServiceWorkerPlugin;