Array.prototype.at

By  on  

Working with arrays is an essential skill in any programming language, especially JavaScript, as we continue to rely on external data APIs. JavaScript has added methods like find and `findIndex recently, but one syntax I love from languages like Python is retrieving values by negative indexes.

When you want to get the value of the last item in an array, you end up with an archaic expression:

const arr = ["zero", "one", "two", "three"];
const last = arr[arr.length - 1];

You could use pop but that modifies the array. Instead you can use at and an index, even a negative index, to retrieve values:

const arr = ["zero", "one", "two", "three"];
arr.at(-1); // "three"
arr.at(-2); // "two"
arr.at(0); // "zero"

at is a very little known function but useful, if only for the shorthand syntax!

Recent Features

  • By
    Welcome to My New Office

    My first professional web development was at a small print shop where I sat in a windowless cubical all day. I suffered that boxed in environment for almost five years before I was able to find a remote job where I worked from home. The first...

  • By
    LightFace:  Facebook Lightbox for MooTools

    One of the web components I've always loved has been Facebook's modal dialog.  This "lightbox" isn't like others:  no dark overlay, no obnoxious animating to size, and it doesn't try to do "too much."  With Facebook's dialog in mind, I've created LightFace:  a Facebook lightbox...

Incredible Demos

  • By
    MooTools Typewriter Effect Plugin

    Last week, I read an article in which the author created a typewriter effect using the jQuery JavaScript framework. I was impressed with the idea and execution of the code so I decided to port the effect to MooTools. After about an hour of coding...

  • By
    Reverse Element Order with CSS Flexbox

    CSS is becoming more and more powerful these days, almost to the point where the order of HTML elements output to the page no longer matters from a display standpoint -- CSS lets you do so much that almost any layout, large or small, is possible.  Semantics...

Discussion

    Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!