jQuery: Why prepend a $ to variable name?

Question

I am trying to learn jQuery and I came across this line in an example.

var $title = $(tag).attr('title');

Can someone please tell me what the prepended $ is for in $title.

The example seems to work fine if I replace $title with just title.

I understand this is probably a stupid question but it is a waste of time googling for "purpose of $"

Many thanks.

It's just to say that it is a jQuery object and that you don't need to $() it again in order to avoid unnecessary function calls. — Arnaud F., Apr 22 '11 at 09:34
possible duplicate of [Why would a JavaScript variable start with a dollar sign?](http://stackoverflow.com/questions/205853/why-would-a-javascript-variable-start-with-a-dollar-sign) — Qantas 94 Heavy, May 27 '14 at 11:25

score 18 · Accepted Answer · answered Apr 22 '11 at 09:29

It doesn't "mean" anything. The $ character is a legal character in Javascript variable names.

However, there is a convention (which isn't universal) of using $ as a prefix to any variable that points to a jQuery selection.

You give the example:

var $title = $(tag).attr('title');

This is a bad use of the $ character, according to this convention. $title is a string, not a jQuery selection.

This would be a correct use of the character:

var $el = $(tag);
var title = $el.attr('title');

Otherwise, a big reason for the prevalence of the $ character is that it is mandatory in PHP, and there is a big overlap between jQuery and PHP programmers.

Thank you very much to all those kind enough to respond. I understand perfectly now. — Pete Davies, Apr 22 '11 at 09:34

score 1 · Answer 2 · answered Apr 22 '11 at 09:30

1

I think people use it as a convention for 'things I looked up with jQuery that I want to hold onto without needing to look up again'.

The one you see most often is var $this = $(this)

answered Apr 22 '11 at 09:30

Will Dean

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score 1 · Answer 3 · edited May 23 '17 at 11:53

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$ is a valid character in javascript variable names. It makes no difference in the snipped you posted. See this related answer.

edited May 23 '17 at 11:53

Community

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answered Apr 22 '11 at 09:31

Jakub Januszkiewicz

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score 1 · Answer 4 · answered Apr 22 '11 at 09:32

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Looks like a PHP developer was getting a bit tired and didn't realise he was in a javaScript code block.

answered Apr 22 '11 at 09:32

psynnott

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score 0 · Answer 5 · answered Apr 22 '11 at 09:35

In JavaScript you don't need to have $ on variable names. However, to access the element using jQuery (usually by the $) you'll need the $ on the ('#selector_id') bit - i.e. $('#selector_id').

The intent of this is to denote to the programmer that the variable is a jQuery wrapper object.

score -1 · Answer 6 · answered Apr 22 '11 at 09:30

-1

In javascript $ is nothing. This is the same as add a to title (atitle). It's just a symbol you can use for names.

answered Apr 22 '11 at 09:30

Emmerman

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score -2 · Answer 7 · answered Apr 22 '11 at 09:29

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there is no purpose for $, it's just named that way. =)

answered Apr 22 '11 at 09:29

Headshota

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read above, it explains the non-universal convention for meaning the variable is a jquery selection – Christopher Thomas Dec 02 '13 at 16:36

score -3 · Answer 8 · answered Apr 22 '11 at 09:29

-3

The symbol '$' is mapped to the jQuery class. There is NO reason to prefix title with '$'.

answered Apr 22 '11 at 09:29

Richard Schneider

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jQuery: Why prepend a $ to variable name?

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