gistfile1.txt

import puppeteer from "puppeteer";
import imagemin from "imagemin";
import imageminWebp from "imagemin-webp";
import Fontmin from "fontmin";
import pino from "pino";

if (process.argv.length < 3) {
	console.error("usage: node main.js url");
	process.exit(1);
}

const logger = pino();

const readBody = (type, response, page) => {
	return new Promise(async resolve => {
		const url = response.url();
		const mime = response.headers()["content-type"];

		logger.debug({ url, mime }, "found " + type);

		try {
			resolve(await response.buffer());
		} catch (err) {
			logger.warn({ url, mime, err }, "failed to fetch " + type);
			resolve(null);
		}
	});
}

const imageHandler = async (type, response, page) => {
	const raw = await readBody(type, response, page);
	if (!raw) return;

	const compressed = await imagemin.buffer(raw, {
		plugins: [
			imageminWebp()
		]
	});

	if (raw.length > compressed.length) {
		const savedBytes = raw.length-compressed.length
		logger.info({ url: response.url(), savedBytes }, "compressed image");

		// TODO: stream to the backend
	}
}
const fontHandler = async (type, response, page) => {
	const raw = await readBody(type, response, page);
	if (!raw) return;

	const fontmin = new Fontmin()
		.use(new Fontmin.ttf2woff2())
		.src(raw);
	const results = await fontmin.runAsync();

	if (results.length > 1) {
		const compressed = results.reduce((a, b) =>
			a._contents.length < b._contents.length ?
				a._contents : b._contents)

		if (raw.length > compressed.length) {
			const savedBytes = raw.length-compressed.length
			logger.info({ url: response.url(), savedBytes }, "compressed font");

			// TODO: stream to the backend
		}
	}
}
const resourceHandlers = {"image": imageHandler, "font": fontHandler};

logger.info("opening browser...");

const browser = await puppeteer.launch();
const page = await browser.newPage();

while (process.argv.length != 2) {
	const url = process.argv[2];

	page.on("response", response => {
		const type = response.request().resourceType();
		resourceHandlers[type]?.(type, response, page);
	});

	logger.info({ url }, "navigating");

	try {
		await page.goto(url);
	} catch {
		logger.error({ url }, "invalid url");
	}

	process.argv.splice(2, 1);
}

//await browser.close();