Articles Tagged JavaScript

When writing code for the web, eventually you'll need to do some process that might take a few moments to complete. JavaScript can't really multitask, so we'll need a way to handle those long-running processes.

Async/Await is a way to handle this type of time-based sequencing. It’s especially great for when you need to make some sort of network request and then work with the resulting data. Let's dig in!

Promise? Promise.

Async/Await is a type of Promise. Promises in … Read article

Page reloads are a thing. Sometimes we refresh a page when we think it’s unresponsive, or believe that new content is available. Sometimes we’re just mad at the dang site and rage-refresh to let it know we’re displeased.

Wouldn’t be nice to know when a user refreshes the page? Not just that, but how many times? That data can help us trigger some sort of behavior after a certain number of reloads.

A sports site is a good example. If … Read article

What's happening when you see some JavaScript that calls super()?.In a child class, you use super() to call its parent’s constructor and super.<methodname></methodname> to access its parent’s methods. This article will assume at least a little familiarity with the concepts of constructors and child and parent classes. If that's totally new, you may want to start with Mozilla's article on Object-oriented JavaScript for beginners.

Super isn't unique to Javascript — many programming languages, including Java and Python, have … Read article

JavaScript has a variety of built-in popup APIs that display special UI for user interaction. Famously:

alert("Hello, World!");

The UI for this varies from browser to browser, but generally you’ll see a little window pop up front and center in a very show-stopping way that contains the message you just passed. … Read article

JavaScript is what they call "single-threaded." As Brian Barbour puts it:

This means it has one call stack and one memory heap.

We all feel a symptom of that regularly in the form of performance jank and non-interactivity on elements or entire sites. If we give JavaScript lots of jobs and it gets really busy doing them, then it's not doing other things, like, say, handling our event handlers quickly.

There has been an interesting point/counter-point combo recently along … Read article

Testing applications is crucially important to ensuring that the code is error-free and the logic requirements are met. However, writing tests manually is tedious and prone to human bias and error. Furthermore, maintenance can be a nightmare, especially when features are added or business logic is changed. We’ll learn how model-based testing can eliminate the need to manually write integration and end-to-end tests, by automatically generating full tests that keep up-to-date with an abstract model for any app.… Read article

The DOM is just a little weird about some things, and the way you deal with attributes is no exception. There are a number of ways to deal with the attributes on elements. By attributes, I mean things like the id in <div id="cool"></div>. Sometimes you need to set them. Sometimes you need to get them. Sometimes there are fancy helper APIs. Sometimes there isn't.… Read article

Date is weird in JavaScript. It gets on our nerves so much that we reach for libraries (like Date-fns and Moment) the moment (ha!) we need to work with date and time.

But we don't always need to use libraries. Date can actually be quite simple if you know what to watch out for. In this article, I'll walk you through everything you need to know about the Date object.… Read article