I am working on a project, in that they have used $$ to select an id/class. I am not sure about this. Can anybody tell me what does this mean. I googled it. But did not get proper answer.

$$("#" + idName + "text").setStyle('background', '#000');

I am working on a project, in that they have used $$ to select an id/class. I am not sure about this. Can anybody tell me what does this mean. I googled it. But did not get proper answer.

$$("#" + idName + "text").setStyle('background', '#000');

• javascript
• jquery

Share Improve this question Follow edited Aug 4, 2016 at 10:13 Mi-Creativity 9,6641010 gold badges4040 silver badges4848 bronze badges asked Aug 4, 2016 at 10:10 Green ComputersGreen Computers 75344 gold badges1717 silver badges2525 bronze badges 6

• I know that $$ in google chrome is the shorthand for document.querySelectorAll, but for use in jQuery? I don't think it makes a difference, but I can't substantiate that. – evolutionxbox Commented Aug 4, 2016 at 10:11
• 1 Possible duplicate of JavaScript Double Dollar Sign – hsz Commented Aug 4, 2016 at 10:12
• Can you post more JS? Specifically the IIFE arguments? – evolutionxbox Commented Aug 4, 2016 at 10:12
• @hsz - I don't think it is a duplicate. That question was asking about a variable name with $$ whereas this looks like a function library usage. – evolutionxbox Commented Aug 4, 2016 at 10:14
• Thank you all. Now i need to find which js library file uses $$ in my project. – Green Computers Commented Aug 4, 2016 at 10:18

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3 Answers 3

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It's simply some library shorthand. Like jQuery assigns itself variable $, some other library may assign $$ to itself to avoid conflicting with jQuery

In Javascript $ is a valid variable name, as is $$ and $$$. While you see it mostly used with jQuery, this is not unique to jQuery.

As another answer says, the project you're working with likely has a library which has assigned something to $$.

$ can also be used in variable names like this:

$foobar
foo$bar

Looking at $$("#" + idName + "text"), the double $ doesn't make any sense to me but would be error in your code as jQuery shorthand alias is just a single $ and when you use $$(selector) would make no sense.

But obviously you can assign the $$ or anything that is valid identifier to work with jQuery to make it no-conflict like below:

var $$ = jQuery.noConflict();
$$(selector); //now here $$ is jQuery alias with no problem

So, I suppose your code is using some library shorthand method jQuery alias as $$.