ffmpeg: batch convert
Say, a bunch of .wav files to .mp3 $ for f in *.wav; do ffmpeg -i $f “${f%.*}.mp3”; done
Downloading top X sites’ data with ZombieJS
Update: Easier way to get top X URLs: http://httparchive.org/urls.php, thanks @souders Update: found and commented an offensive try{}catch(e){throw e;} in zombie.js (q.js, line 126), now the script doesn’t fatal that often Say you want to experiment or do some research with what’s out there on the web. You need data, real data from the web’s […]
Jest + jQuery for testing a vanilla “app”
Jest is a new javascript testing tool announced today. I thought I’d take it out for a spin testing the UI of a simple vanilla JS app – no CommonJS modules, no fancy stuff. Just old school JavaScript. Granted, it’s probably not what the tool was optimized to do, but it totally worked. The app […]
CSS diffs #2
Continuing from last night… First, two twitter responses pointed to even more readily-available options for comparing screenshots. One is Wraith from BBC engineers which supports Firefox/Gecko (via SlimerJS) in addition to PhantomJS. The other is the almost-ready siteeffect.io which is based on http://dalekjs.com/ which seems to support all the browsers! Anyway, I thought I should […]
css diff
CSS is the worst because it blocks page rendering. The bigger it grows, the more it blocks. And bigger is what CSS becomes if left unattended, as anyone who has worked on any project for more than a few days or with more than a few people can confirm. So occasionally one must step back […]
DIY source maps
In today’s world of always having some sort of code transformation before your JS/CSS/HTML reaches the user, e.g. minification, concatenation, es6-to-es3 transpilation, it’s nice to be able to go back to the source before the transformation. And when that happens in the comfort and the immediacy of the browser’s dev tools, even better! Enter source […]
Writing ES6 today with jstransform
So there’s this recent open-source project from Facebook called jstransform. It’s also used by ReactJS. It lets you explore ES6 features and not only explore, but use them in production code. All you need to do is add the transformation to your static resource pipeline. (Of course you have one, right, for minification and so […]
Beacon performance
Beacons are small requests that our apps make to report some information “home”, to the server. Beacons are often used to report visitor stats, JS errors, performance metrics. Beacons often don’t return any data back to the client, but some do. Example use <div id="app">Awesome app is awesome</div> <script> // gather data somehow var data […]
Hello subpixel world
Since IE9 and Firefox(v.?) we now have subpixel rendering of fonts. This is cool and all but imagine this: you have some text you want to measure the width of the text and size another element to the same dimensions Simple. But if you use offsetWidth/offsetHeight to measure, you get a rounded integer and not […]
ReActiveTable bookmarklet
Previously… React and tables. I’ve been meaning to improve a little on the table example built with React and a post by Steve was the final push. He shared his “ActiveTable” bookmarklet. So, introducing a bookmarklet to make it easier to work with random HTML tables you come across… ReActiveTable Drag this link to your […]
NYC.bind(me)
On my way to NYC for Edge conference and NYC Web perf meetup. Some slides and RSVP links inside.
Server-side React with PHP – part 2
Part 1 ended with todos. The first one was to couple the server-side generated code with the client-side React, so that any updates past the initial page load will be handled by React’s client JS, which is where React shines. Let’s see how you can do just that. PHP data fetch, gluing JS for v8 […]
Borrowing typography tricks from the masters
Inspect the styles in Mobile Safari’s Reader feature to learn typography
Server-side React with PHP
Problem: Build web UIs Solution: React Problem: UI built in JS is anti-SEO (assuming search engines are still noscript) and bad for perceived performance (blank page till JS arrives) Solution: React page to render the first view Problem: Can’t host node.js apps / I have tons of PHP code Solution: Use PHP then! This post […]
Installing v8js for PHP on a Mac
Motivation? Run JS code inside PHP. Just… because 🙂 I struggled for a while with this installation, so leaving a trail here for anyone looking. What you need to accomplish? Goal: run JS code inside a PHP script running on a webserver. Already accomplished: Macs come with a webserver (Apache) and PHP. To get there: […]
Reactive table
In the previous post I mentioned the pains, misery and suffering attached to creating and updating an HTML table in DOM land. Now let’s see how you do this simple task in React. Demo React is all about components. So let’s build one. Let’s call it Table (to avoid any confusion what the component is […]
Remarkable React
I gave a talk about React at BrazilJS few days ago. The “slides” are here. In this post I’ll go over what I said (more or less) at the beginning of the presentation. I hope to follow up with some more code. Disclaimer: I work at Facebook. But these are my thoughts. In fact, I […]
Here’s to a faster Recommendations plugin
So I’ve been part of the quest of making all Facebook social plugins faster, even if it means rewriting them from scratch. After the Send plugin, Like button (perf optimizations described here), Follow plugin, Facepile and Likebox (perf details here), now you have a faster Recommendations plugin. The techniques used to make it faster are […]
CSS animations off the UI thread
This excellent Google I/O talk mentions that Chrome for Android moves the CSS animations off of the UI thread, which is, of course, a great idea. Playing around with it, here’s what I found: Browser support: Desktop Safari, iOS Safari, Android Chrome. You need to use CSS transforms. Animating regular properties doesn’t work. Update: (see […]
C3PO: Common 3rd-party objects
Problem: too much JavaScript in your page to handle 3rd party widgets (e.g. Like buttons) Possible solution: a common piece of JavaScript to handle all third parties’ needs What JavaScript? If you’ve read the previous post, you see that the most features in a third party widget are possible only if you inject JavaScript from […]
Speed geek’s guide to Facebook buttons
or “How to help your users share your content on Facebook and not hurt performance” Facebook’s like button is much much faster now than it used to be. It also uses much fewer resources. And lazy-evaluates JavaScript on demand. And so on. But it’s still not the only option when it comes to putting a […]
Run jsperf tests in a bunch of WebPagetest browsers
Motivation 1. You write a new test to confirm a JavaScript-related performance speculation 2. You click 3. Your test runs in a bunch of browsers Glossary JSperf.com is the site where all you JavaScript performance guesswork should go to die or be confirmed. You know how the old wise people say “JSperf URL or it […]
webkit css-on-demand issues
This post brought to you via Facebook engineers Jeff Morrison and Andrey Sukhachev, who discovered and helped isolate the issue. Use case Think a “single page app” use case. You click a button. Content comes via XHR. But content is complex (and app is as lazy-loading as possible) and content requires extra CSS. In an […]
Digging into the HTTP archive #2
Continuing from earlier tonight, let’s see how you can use the HTTP archive as a starting point and continue examining the Internet at large. Task: figure out what % of the JPEGs out there on the web today are progressive vs baseline. Ann Robson has an article for the perfplanet calendar later tonight with all […]
Digging into the HTTP archive
Update: Second part One way to do web performance research is to dig into what’s out there. It’s a tradition dating back from Steve Souders and his HPWS where he was looking at the top 10 Alexa sites for proof that best practices are or aren’t followed. This involves loading each pages and inspecting the […]
