sp-dev-fx-webparts/samples/react-script-editor/gulpfile.js

'use strict';

const gulp = require('gulp');
const path = require('path');
const build = require('@microsoft/sp-build-web');
const bundleAnalyzer = require('webpack-bundle-analyzer');

build.configureWebpack.mergeConfig({
  additionalConfiguration: (generatedConfiguration) => {
    const lastDirName = path.basename(__dirname);
    const dropPath = path.join(__dirname, 'temp', 'stats');
    generatedConfiguration.plugins.push(new bundleAnalyzer.BundleAnalyzerPlugin({
      openAnalyzer: false,
      analyzerMode: 'static',
      reportFilename: path.join(dropPath, `${lastDirName}.stats.html`),
      generateStatsFile: true,
      statsFilename: path.join(dropPath, `${lastDirName}.stats.json`),
      logLevel: 'error'
    }));

    return generatedConfiguration;
  }
});

build.initialize(gulp);