Articles Tagged JavaScript

You might not know this, but JavaScript has stealthily accumulated quite a number of observers in recent times, and Intersection Observer is a part of that arsenal. Observers are objects that spot something in real-time — like birdwatchers going to their favorite place to sit and wait for the birds to come.

Different observers observe different things (not everyone watches hawks).

The very first observer I came to know was the Mutation Observer that looks for changes to the DOM … Read article “A Few Functional Uses for Intersection Observer to Know When an Element is in View”

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 “In Defense of the Ternary Statement”

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 “Undefined: The Third Boolean Value”

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.

A screenshot of the bug report filed with Mozilla.

The problem, the developer noted in his … Read article “Yet Another JavaScript Framework”

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 “Differential Serving”

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 “An Illustrated (and Musical) Guide to Map, Reduce, and Filter Array Methods”

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 “Understanding Event Emitters”