A quick survey… So my onlinemusictools.com is a bunch of little React apps. I was wondering – is the JS-generated content of the apps visible in search engines? A quick survey was in order. The answer is – out of Google, Bing, DuckDuckGo, Yandex, only Google search crawler speaks the lingua JavaScript. Google screenshot below. […]

Maybe you’re an attacker who sneaked in a little JavaScript to an unsuspecting site and would like to, well, sneak. Or maybe you want to know what exactly all these third-party analytics scripts are “calling home”. Or maybe just for fun – wouldn’t it be cool to intercept and log all requests made with new […]

Yesterday I had to plug in my keyboard to the computer and wasn’t sure if it was working. How do I test? Well, I had to look up an older post, copy and paste some code to the console… what a drag. I though it would be cool to have a page where you can […]

Here’s my new tool called intervals Play with it here. Learn about the theory behind it here. The code for the tool. What does it do? Generates a random music interval, shows it on the musical staff. You try to guess it. Clicking on the staff reveals the answer. You can also play the interval. […]

There’s a new tool in town. It lets you drag photos and gives you a map of where the photo was taken. Creepy, isn’t it? It figures this out using the meta (exif) information that’s part of a photo. The tool also lets you download a version of the photo without any exif information. The […]

(this industry and its lingo…) PWA – Progressive Web App, it’s… a long story, go read here React – library for building UIs. There’s a book on React by yours truly. create-react-app – a tool that generates skeleton React apps sw-precache – a tool that helps turn any web app into a PWA Before This […]

Every once in a while I feel inspired to create a little tool to “do one thing” ™. But often I get distracted and a little too lazy to get off the ground and forget all about it. So I thought maybe a little helper can, well, help move things along. Enter FAIL, short for […]

Ever needed a list of all the countries in the world to put as options in an HTML select? Well, here you go. And JSON too. You’re welcome! But how… How was the list derived so you can update it once in a while? Glad you asked. https://www.iso.org/obp/ui/#search/code/ is the page linked from W3 spec […]

Inspired by this talk by Jean-Philippe Côté I saw at Web Unleashed in Toronto last month, I thought I should dust off the old midi cable. MIDI? MIDI is a protocol that various music and lighting devices use to talk to each other. Believe it or not v1.0 of the spec from 1983 is still […]

I’m a little late (like, omgbbq, 2 months late) with this announcement, but here goes: I published my new book, called “React: Up and Running”. Go get it everywhere where books are sold and learn React from the ground up! I’ve been working with React for a while now and thought I have something to […]

Warning: don’t do this. Stop it! Just. Don’t. So there’s this hack by Ben Foxall that shows how you can escape the browser window and draw outside the page. I had to try it myself. So here comes: the animated “progress” indicator mouse cursor. Wait what? There exists the ability for your web page to […]

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 […]

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 […]

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 […]

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 […]

On my way to NYC for Edge conference and NYC Web perf meetup. Some slides and RSVP links inside.

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 […]

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 […]

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: […]

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 […]

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 […]

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 […]

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 […]

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 […]

Live input, aka getUserMedia: it exists in Chrome Canary for audio too. Great times to be a web developer, right? Let’s check it out. Here’s the demo, but first a prerequisite: go chrome://flags, search for “Web Audio Input” and enable it. Restart Chrome Canary. With a guitar I wanted to have a little trickier setup […]