What does jQuery(function($){something}); do?

Question

I've never seen anyone do this before. Could anyone enlighten me on this? This was taken from here.

jQuery(function ($) { //What's with the $ as an argument? $('#flux').bind('scroll', function () { if ($(this).scrollTop() + $(this).innerHeight() >= $(this)[0].scrollHeight) { alert('end reached'); } }) });

It appears he can declare a function and run it at the same time.

Is this question about the "$" argument only, or is this the first time you encounter jQuery code? — Pierre Arlaud
– Pierre Arlaud, Commented Apr 7, 2014 at 9:23
@ArlaudPierre No sir, I wasn't aware that this was another way to do $(document).ready();. On another note, I just tested the function without the $ argument and it works regardless. Does it serve any purpose? — geoyws
– geoyws, Commented Apr 7, 2014 at 9:35
@Geoyws check out the discussion I had with Misiur on his answer, it's here "to avoid conflicts with some other global $ variable". — Pierre Arlaud
– Pierre Arlaud, Commented Apr 7, 2014 at 9:36

Misiur · Accepted Answer · 2014-04-07 09:19:55Z

2

It's shorthand for http://api.jquery.com/ready/

The argument $ is in fact jQuery - it's often used to avoid conflicts with some other global $ variable

See: http://api.jquery.com/jQuery/#jQuery3

answered Apr 7, 2014 at 9:19

Misiur

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4 Comments

Pierre Arlaud Over a year ago

No example of the page uses "$" as the function argument.

Misiur Over a year ago

I'm not sure if I understand you correctly, but in the second link the last example uses $ as an argument. It's kinda like closures, where you pass global variables, but aliased: (function($, hello, undefined) { /* ... */ })(jQuery, 'something');

Pierre Arlaud Over a year ago

Oh okay, I only check it on the ready page, my bad. Do we know of any other plugin that conflicts with jQuery?

Misiur Over a year ago

learn.jquery.com/using-jquery-core/… - prototype used to be a big problem, also better safe than sorry!

Thilo · Accepted Answer · 2014-04-07 09:54:32Z

It appears he can declare a function and run it at the same time.

The function is not run here, it is just passed to jQuery (which will run it when the document is ready).

function ($) { //What's with the $ as an argument?

This is the Javascript concept of a module:

Instead of having the function refer to a global $ (which may end up being something unexpected), you pass in the $ as a parameter (jQuery will do that for you here). Then within the function body $ refers to that local object.

I just tested the function without the $ argument and it works regardless.

Yes, but that is because you also have a global object $. The idea of passing it in explicitly is to avoid having the function access the global scope.

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