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Use $ & $$ Instead of document.querySelector/All in JavaScript without jQuery

Ahmad Awais ⚡️ on April 02, 2019

I started writing JavaScript code because of WordPress back in 2007. JavaScript was not what it is today. It would behave differently on different ...

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Den McHenry • Apr 2 '19

If you work on a distributed team or with legacy code, and considering the potential for conflict (mostly with jQuery but some other libraries, and any code where someone may have used $ for document.getElementById(), as used to be common), I think it'd be a good idea to use trivially longer identifiers like this:

const $q = document.querySelector.bind(document);
const $qa = document.querySelectorAll.bind(document);

This is similar to a common method of using jQuery in noConflict mode, e.g.:

const $j = jQuery.noConflict();

It could be judiciously extended for similar methods if you use them often enough.

Tgwizman • Apr 2 '19

I have been using
$ = function(e) {return document.getElementById(e)}
for years. Now I started using
$ = function(e) {
switch (e[0]) {
case '.': return document.getElementsByClassName(e.substring(1, e.length)); break;
case '#': return document.getElementById(e.substring(1, e.length)); break;
default: return document.getElementsByTagName(e);
}
}

Andrea Giammarchi • Apr 3 '19

Chrome has its own Console Utilities API Reference where $ and $$ are offered regardless, among other utils, unless the global scope has been overwritten with something else (i.e. jQuery).

The API for $ and $$ is more jQuery-ish, and if you'd like to reproduce it its like:

const $ = (css, parent = document) => parent.querySelector(css);
const $$ = (css, parent = document) => parent.querySelectorAll(css);

To avoid needing polyfills for forEach or Symbol.iterator on NodeList collections, you can also go ahead and convert the static collection as Array so that all methods, including filter and map can be used.

const $$ = (css, parent = document) =>
  Array.from(parent.querySelectorAll(css));

If you don't have Array.from in your debug session, or you are after a thin layer that works across browsers, you can go for the following:

function $(css, parent) {
  return (parent || document).querySelector(css);
}

function $$(css, parent) {
  var nodes = (parent || document).querySelectorAll(css);
  return Array.prototype.slice.call(nodes, 0);
}

Massimo Artizzu • Apr 3 '19

Watch out that querySelectorAll returns a NodeList object, whereas $$ in the console returns an array.

So if you're used to call all the sweet array prototype methods, you might fall short!

Solution: wrap everything in Array.from.

Ahmad Awais ⚡️ • Apr 3 '19

Thanks for reminding us :)

Tormod Vold Mikkelsen • Oct 16 '19

This is my take on it. It checks whether I'm asking for an id or not, and if I am, it returns just that one element. If not, the NodeList is made into an array.

const $ = (q, d = document) => 
  /#\S+$/.test(q)                       // check if query asks for ID
  ? d.querySelector.bind(d)(q)          // if so, return one element
  : [...d.querySelectorAll.bind(d)(q)]  // else, return all elements in an array.

Itachi Uchiha • Apr 3 '19

I'm using document.querySelectorAll for all elements. Even for id elements.

Actually, you can use querySelectorAll for id elements. It will work for one element. There must not be multiple elements in a document that have the same id value.

const $ = document.querySelectorAll.bind(document)

const testEl = $("#test")

testEl.forEach(el => {
    console.log(el)
})

Hendra Susanto • Apr 3 '19

Instead of using 2 different constants, what about checking the length of the selector first like this:

const $ = s => document.querySelectorAll.bind(document)(s).length > 1 ? document.querySelectorAll.bind(document)(s) : document.querySelector.bind(document)(s);

or something like that to make it much more similar to jQuery $?

Thibaut Allender • Apr 4 '19

From a performance perspective, that would double the amount of work for every selector. Going from jQuery to Vanilla JS is mostly about being more performant, so that looks like an anti-pattern.

Ahmad Awais ⚡️ • Apr 6 '19

Can you explain how would that be the double amount of work? It's just one extra call.

Thibaut Allender • Apr 10 '19

It's 2 calls instead of one, so it's double.

Eljay-Adobe • Apr 2 '19 • Edited

Ugh, I had to replace jQuery in our app with a work-a-like jQuery that I wrote. It was THE WORST, because I had to learn jQuery, then I learned all about jQuery's internals, then I had to figure out the subset of jQuery that we depended upon that did not have all the internal state that jQuery had (did everyone know jQuery has a ton of internal state?), then I had to put up with all the upset other JavaScript developers who complained about my not-jQuery not behaving like jQuery when they added new code that relied on jQuery-isms that I hadn't implemented because the prior versions of the code hadn't relied upon those facilities (so I didn't bother to implement them).

What a royal pain in the keester.

I wish I had the foresight to just do your $ and $$ bindings and tell all the other devs to suck it up. Your solution is GENIUS.

Tommy Williams • Jan 22 '20

Could you explain the purpose of creating your jQuery-like library? I don't understand what you gained, compared to just continuing to use jQuery.

Eljay-Adobe • Jan 23 '20

The lawyers at my company would not allow us to ship or use third party libraries.

Marek • Oct 8 '19

const $ = (selector, base = document) => {
   let elements = base.querySelectorAll(selector);
   return (elements.length == 1) ? elements[0] : elements;
}

Kevin McKenna • Apr 2 '19

I'm interested in your thoughts a little deeper on this:

"I advocate modern JavaScript. Because it's super awesome." - Why would you advocate modern JavaScript ahead of jQuery beyond it being awesome. What do you feel is the main selling point is that can't be accomplished in other ways?

Cedric W • Apr 2 '19

This looks cool.

with you example could you still do this though?

const username = 'johndoe'
const age = 32

console.log(`The name of the user is ${username} and his age is ${age}.`)

JavaScript Joel • Apr 2 '19 • Edited

Yep, it would look like this:

const username = 'johndoe'
const age = 32

console.log(`The name of the user is ${username} and his age is ${age}.`)
console.log(`Element is: ${$('#article-reaction-actions')}.`)

The outer $ in the template string will start the evaluation. the $ inside of ${} will refer to the global $.

Hope this clears it up!

Cedric W • Apr 2 '19

now that I think about it, I guess this would be a scope issue

Jason R Tibbetts • Apr 2 '19 • Edited

👍

This is an awesome tip!

Vincent Milum Jr • Apr 2 '19

Things like this are AMAZING so long as you don't have to support any legacy systems. It's nice to see that the feature set built by jQuery is essentially built into the browser directly now, and a simple wrapper gives us similar functionality.

florent giraud • Apr 3 '19

I already did this in some projects that's cool !
But one point to take care is about performance.
Because querySelector do a lot more jobs thant getElementsById or class so if you dont care about perf you solution is perfect

Niko Solihin • Apr 3 '19

Great tip Ahmad.

Also, in Chrome dev tools, $ and $$ are already bound by default to querySelector and querySelectorAll respectively.

intrnl • Apr 3 '19

Isn't $ and $$ already binded to querySelector and querySelectorAll from the start though? Which means that binding it again seems unnecessary.

or I suppose the default binding is recent..?

Lazar Ljubenović • Apr 4 '19

I made a module exactly for these purposes just recently: gimme back my dollars! It has a very distinctive name.

vaaski • Apr 3 '19 • Edited

one question.
i always did it like this:

const $ = s => document.querySelector(s)

what are the differences?

Usama Ejaz • Apr 3 '19

this

Perlat Kociaj • Apr 2 '19

Great tip Ahmad.
Thank you for sharing.

Roso Sasongko • Aug 5 '20

...and finally we returned to jQuery

sesay • Apr 2 '19

cool :)