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@martinschierle
martinschierle / cwv_crawler.js
Last active Aug 3, 2020
Small puppeteer script to run over a domain, crawl random urls, capture screenshots with lcp and cls elems highlighted, and also writing out a heatmap of lcp and cls bounding boxes across all crawled pages.
View cwv_crawler.js
const puppeteer = require('puppeteer');
const { createCanvas, loadImage } = require('canvas')
const mustache = require('mustache')
var fs = require('fs');
const fsExtra = require('fs-extra')
let MAX_URLS = 50;
let TEMPLATE = fs.readFileSync('template.html', 'utf8');
View *polkompress.md

Polkompress

A tiny zero-dependency compression middleware for polka (& express!) with native Brotli support.

@martinschierle
martinschierle / sw_performance_check.js
Last active Jul 22, 2020
Puppeteer script to check performance of a page with and without service worker
View sw_performance_check.js
// Idea and some code stemming from https://michaljanaszek.com/blog/test-website-performance-with-puppeteer#cacheAndServiceWorker
const puppeteer = require('puppeteer');
const devices = require('puppeteer/DeviceDescriptors');
const {URL} = require('url');
var fs = require('fs');
var sw_scope;
let NETWORK_PRESETS = {
'GPRS': {
'offline': false,
@fletcherist
fletcherist / CpuMeter.js
Created Oct 11, 2017
CPU Metrics for Chrome Extensions
View CpuMeter.js
((name, context = window, func) => { context[name] = func() })
('CpuMeter', this, () => {
const isEmptyObject = object => Object.keys(object).length === 0
const getProcessorUsage = (usage, oldUsage) =>
Math.floor((usage.kernel + usage.user - oldUsage.kernel - oldUsage.user) / (usage.total - oldUsage.total) * 100)
class CpuMeter {
constructor() {
if (!chrome || !chrome.system || !chrome.system.cpu) {
throw new Error(`No access to chrome.system.cpu!
@krisselden
krisselden / index.js
Created Apr 3, 2017
Chrome Code Coverage Automation
View index.js
import * as fs from "fs";
import { createSession } from "chrome-debugging-client";
createSession(async (session) => {
let browser = await session.spawnBrowser("canary");
let api = await session.createAPIClient("localhost", browser.remoteDebuggingPort);
let tabs = await api.listTabs();
let tab = tabs[0];
let client = await session.openDebuggingProtocol(tab.webSocketDebuggerUrl);
await client.send("Profiler.enable");
@Rich-Harris
Rich-Harris / module-loading.md
Last active Sep 2, 2020
Dynamic module loading done right
View module-loading.md

Dynamic module loading done right

Follow-up to Top-level await is a footgun – maybe read that first

Here are some things I believe to be true:

  1. Static module syntax is beneficial in lots of ways – code is easier to write (you get better linting etc) and easier to optimise (tree-shaking and other things that are only really possible with static syntax), and most importantly, faster to load (it's trivial for a module loader to load multiple dependencies concurrently when they're declared with a static syntax – not so with imperative statements like require(...) or await import(...)).
  2. App startup time is perhaps when performance is most critical. (You already know this, I don't need to cite the studies.)
  3. If you're in favour of constructs that jeopardise app startup time, you are anti-user. Top-level await is such a construct.
@ebidel
ebidel / polymer-perf-bookmarklet.js
Last active Mar 16, 2020
Polymer performance numbers bookmarklet
View polymer-perf-bookmarklet.js
javascript:(function(){(function printStats(){var loadTimes=window.chrome.loadTimes();firstPaint=loadTimes.firstPaintTime*1000;firstPaintTime=firstPaint-(loadTimes.startLoadTime*1000);console.info('First paint took',firstPaintTime,'ms');console.info('Load took',performance.timing.loadEventStart-performance.timing.navigationStart,'ms');var instances=0;if(parseFloat(Polymer.version)<1){instances=[].slice.call(document.querySelectorAll('html /deep/ *')).filter(function(el){return el.localName.indexOf('-')!=-1||el.getAttribute('is');}).length;}else{instances=Polymer.telemetry.instanceCount;}console.info('Custom element instances:',instances);var reflectCount=0;if(Polymer.telemetry){console.info('=== Properties set to reflectToAttribute ===');Polymer.telemetry.registrations.forEach(function(el){for(var prop in el.properties){if(el.properties[prop].reflectToAttribute){console.log(el.is+'.'+prop);reflectCount++;}}});}else{console.info('=== Properties set to reflect ===');Polymer.elements.forEach(function(el){for(var
@jmiserez
jmiserez / export_google_music.js
Last active Oct 20, 2020
(fixed/updated 2016-05-10) Export your Google Music Library and Playlists (Google Play Music All Access) (see http://webapps.stackexchange.com/questions/50311/print-playlist-from-google-play-music for more)
View export_google_music.js
// Copyright 2016 Jeremie Miserez <jeremie@miserez.org>
//
// MIT License
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF O
@bmeck
bmeck / partial_application.js
Last active Aug 29, 2015
simple tagged template functions
View partial_application.js
let tee = (a) => {console.log(String(a)); return a}
// our applicator
let $_ = (n) => {
let args = new Array(n);
for (let i = 1; i <= n; i++) {
args[i-1] = `$${i}`
}
return (raw, ...values) =>
Function(...args.concat(tee('return ' + raw.reduce(
@sindresorhus
sindresorhus / np.sh
Last active Nov 14, 2019
shell function for publishing node modules with some goodies
View np.sh
# npm publish with goodies
# prerequisite: `npm install -g trash`
# `np` with an optional argument `patch`/`minor`/`major`/`<version>`
# defaults to `patch`
np() {
trash node_modules &>/dev/null;
git pull --rebase &&
npm install &&
npm test &&
npm version ${1:-patch} &&
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