Articles Tagged JavaScript

Some months ago I was on Hacker News (as one does) and I ran across a (now deleted) article about not using if statements. If you’re new to this idea (like I was), you’re in a for a real treat. Just search for "if statements" on Hacker News. You'll get articles proposing that you might not need them, articles that refer to them as a code smell and even the quintessential "considered harmful." Listen, you know a programming … Read article

I wanted to implement a notification message in one of my projects, similar to what you’d see in Google Docs while a document is saving. In other words, a message shows up indicating that the document is saving every time a change is made. Then, once the changes are saved, the message becomes: “All changes saved in Drive.”

Let’s take a look at how we might do that using a boolean value, but actually covering three possible states. This definitely … Read article

On March 6, 2018, a new bug was added to the official Mozilla Firefox browser bug tracker. A developer had noticed an issue with Mozilla's nightly build. The report noted that a 14-day weather forecast widget typically featured on a German website had all of a sudden broken and disappeared. Nothing on the site had changed, so the problem had to be with Firefox.

The problem, the developer noted in his … Read article

There is "futuristic" JavaScript that we can write. "Stage 0" refers to ideas for the JavaScript language that are still proposals. Still, someone might turn that idea into a Babel plugin and it could compile into code that can ship to any browser. For some of these lucky proposals, Stage 0 becomes 1, 2, 3, and, eventually, an official part of the language.

There used to be a point where even the basic features of ES6 were rather experimental. … Read article

Map, reduce, and filter are three very useful array methods in JavaScript that give developers a ton of power in a short amount of space. Let’s jump right into how you can leverage (and remember how to use!) these super handy methods.… Read article

Consider, a DOM Event:

const button = document.querySelector("button");

button.addEventListener("click", (event) => /* do something with the event */)

We added a listener to a button click. We’ve subscribed to an event being emitted and we fire a callback when it does. Every time we click that button, that event is emitted and our callback fires with the event.

There may be times you want to fire a custom event when you’re working in an existing codebase. Not specifically a DOM … Read article

Rik Schennink documents a system for being able to write CSS selectors that style a page when it has scrolled to a certain point. If you're like me, you're already on the lookout for document.addEventListener('scroll' ... and being terrified about performance. Rik gets to that right away by both debouncing the function as well as marking the event as passive.… Read article

Steve Souders, "JavaScript Dominates Browser CPU":

Ten years ago the network was the main bottleneck. Today, the main bottleneck is JavaScript. The amount of JavaScript on pages is growing rapidly (nearly 5x in the last 7 years). In order to keep pages rendering and feeling fast, we need to focus on JavaScript CPU time to reduce blocking the browser main thread.

Alex Russell, describing a prototype of "Never-Slow Mode" in Chrome:

... blocks large scripts, sets budgets for certain