Articles Tagged JavaScript

Writing asynchronous JavaScript without using the Promise object is a lot like baking a cake with your eyes closed. It can be done, but it's gonna be messy and you'll probably end up burning yourself.

I won't say it's necessary, but you get the idea. It's real nice. Sometimes, though, it needs a little help to solve some unique challenges, like when you're trying to sequentially resolve a bunch of promises in order, one after the other. A trick … Read article

Let's say you wanted to move the background-position on an element as you mouse over it to give the design a little pizzazz. You have an element like this:

<div class="module" id="module"></div>

And you toss a background on it:

.module {
  background-image: url(big-image.jpg);
}

You can adjust the background-position in JavaScript like this:

const el = document.querySelector("#module");

el.addEventListener("mousemove", (e) => {
  el.style.backgroundPositionX = -e.offsetX + "px";
  el.style.backgroundPositionY = -e.offsetY + "px";
});

This is a possible upcoming feature for mobile Chrome:

If a Data Saver user is on a 2G-speed or slower network according to the NetInfo API, Chrome disables scripts and sends an intervention header on every resource request. Users are shown a UI at the bottom of the screen indicating the page has been modified to save data. Users can enable scripts on the page by tapping “Show original” in the UI.

.filter is a built-in array iteration method that accepts a predicate which is called against each of its values, and returns a subset of all values that return a truthy value.

That is a lot to unpack in one statement! Let's take a look at that statement piece-by-piece.… Read article

Managing state is not a new thing in software, but it’s still relatively new for building software in JavaScript. Traditionally, we’d keep state within the DOM itself or even assign it to a global object in the window. Now though, we’re spoiled with choices for libraries and frameworks to help us with this. Libraries like Redux, MobX and Vuex make managing cross-component state almost trivial. This is great for an application’s resilience and it works really well with a state-first, … Read article

By now, we all know that the major tech behemoths like Facebook or Google know everything about our lives, including how often we go to the bathroom (hence all the prostate medication ads that keep popping up, even on reputable news sites). After all, we’ve given them permission to do so, by reading pages and pages of legalese in their T&C pages (we all did, didn’t we?) and clicking on the "Accept" button.

But what can a site do to … Read article

I was recently mentoring someone who had trouble with the .reduce() method in JavaScript. Namely, how you get from this:

const nums = [1, 2, 3]
let value = 0

for (let i = 0; i < nums.length; i++) {
  value += nums[i]
}

...to this:

const nums = [1, 2, 3]
const value = nums.reduce((ac, next) => ac + next, 0)

They are functionally equivalent and they both sum up all the numbers in the array, but there is … Read article

Sublime Text is one of the most popular editors for web development and software development in general. It’s very smooth and fast compared to other editors (being written in C++ helps that speed). Sublime also has tons of plugins you can find through Package Control.

But it’s only a text editor and not an IDE. An IDE is a software application that provides comprehensive facilities to computer programmers for software development. In fact, Sublime doesn’t offer features like … Read article

I used to think implementing swipe gestures had to be very difficult, but I have recently found myself in a situation where I had to do it and discovered the reality is nowhere near as gloomy as I had imagined.

This article is going to take you, step by step, through the implementation with the least amount of code I could come up with. So, let's jump right into it!… Read article