Logical Assignment Operators

By  on  

I love JavaScript, it's my favorite programming language, but I love dipping into other languages because they offer a new perspective on coding paradigms. There've been syntax additions to JavaScript that I've seen I found interesting (think ?? in optional chaining) and now we get more -- logical assignment operators. Let's check out how they can be used!

||=

Or-Or-Equals is used to assign a value when one doesn't exist:

let name;
const defaultName = "Guest";

name ||= defaultName;
// name >> "Guest"

// Equivalent: name || (name = defaultName);

??=

Question-Question-Equals assigns value when the value is undefined:

const j = 1;
j??= 10
// j >> 1

x = undefined;
x ??= 10
// x >> 10

&&=

And-And-Equals assigns value to the last in line when both are defined:

let name;
const defaultName = "Guest";

name &&= defaultName;
name >> undefined

// Both have values
let name = "David";
const defaultName = "Guest";

name &&= defaultName;
// name >> "Guest"

// Equivalent: name && (name = defaultName);

I do worry, at least in the short term, that this new syntax could be hard to maintain, but just like every other new language feature, we'll get used to it!

Recent Features

Incredible Demos

  • By
    CSS Transforms

    CSS has become more and more powerful over the past few years and CSS transforms are a prime example. CSS transforms allow for sophisticated, powerful transformations of HTML elements.  One or more transformations can be applied to a given element and transforms can even be animated...

  • By
    How to Create a Twitter Card

    One of my favorite social APIs was the Open Graph API adopted by Facebook.  Adding just a few META tags to each page allowed links to my article to be styled and presented the way I wanted them to, giving me a bit of control...

Discussion

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