build-sw.js

const fs = require('fs-extra')
const pathmodule = require('path')
const workbox = require('workbox-build')
function build() {
	const cwd = process.cwd();
	const pkgPath = `${cwd}/node_modules/workbox-sw/package.json`;
	const pkg = require(pkgPath);
	const readPath = `${cwd}/node_modules/workbox-sw/${pkg.main}`;
	let data = fs.readFileSync(readPath, 'utf8');
	let path = `${cwd}/build/workbox-sw.js`;
	console.log(`Writing ${path}.`);
	fs.writeFileSync(path, data, 'utf8');
	data = fs.readFileSync(`${readPath}.map`, 'utf8');
	path = `${cwd}/build/${pathmodule.basename(pkg.main)}.map`;
	console.log(`Writing ${path}. ${pkg.main}`);
	fs.writeFileSync(path, data, 'utf8');
	workbox.injectManifest({
		globDirectory: './build/',
		globPatterns: ['**/*.{html,js,css,png,jpg,json}'],
		globIgnores: ['sw-default.js', 'service-worker.js', 'workbox-sw.js', '200.html', 'index.html'],
		swSrc: './sw-template.js',
		swDest: './build/sw-default.js',
		maximumFileSizeToCacheInBytes: 4 * 1024 * 1024, // 4Mb

	}).then(({ count, size, warnings }) => {
		// Optionally, log any warnings and details.
		warnings.forEach(console.warn)
		console.log(`${count} files will be precached, totaling ${size} bytes.`)
	});
}
try {
	build();
} catch (e) {
	console.log(e);
}