Do I need to put a dollar before variable names with javascript?

Question

I have the following code:

var formSubmitHandler = function (link, form) {

    //e.preventDefault();
    var $form = form;
    var val = $form.valid();
    var action = $(form).data('action');
    var entity = $(form).data('entity');

Do I need the line "var $form = form"? Can I just later on do "var val = form.valid(); ?

It's not my code so I am wondering why the developer added the $ before the form and assigned it?

Update:

Thanks for all your replies. If as has been said it's just to indicate that it's a jQuery variable then could I just remove that line by changing the function parameters to (link, $form) ?

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) — Wesley Murch, May 04 '12 at 06:05
Sometimes, the `$` before a variable name is to indicate that it is a jQuery object and not, say, a raw DOM element. That is, you might say `var $this = $(this)` with the `$` in front to indicate that it's a jQuery object. On the other hand, you might have `var element = document.getElementById('test')`. It's all up to the developer, of course. — Reid, May 04 '12 at 06:05

Tx3 · Accepted Answer · 2015-12-17T12:14:07.460

12

$ and jQuery are basically the jQuery instance.

It's good to understand that $( < place something here >) is a jQuery function call and $your_variable_name is just a variable with a dollar.

Some people use $ in their own variables to indicate that it is a jQuery object. With this naming convention, your source code would like this.

var formSubmitHandler = function (link, form) {
    var $form = $(form);
    var val = $form.valid();
    var action = $form.data('action');
    var entity = $form.data('entity');

edited Dec 17 '15 at 12:14

answered May 04 '12 at 06:11

Tx3

6,796
4
37
52

2

`Some people use $ in their own variables to indicate that it is a jQuery object.` just to note that it's used also in plain JS to indicate it's an HTMLElement reference. – Roko C. Buljan Jun 07 '14 at 12:41
1

I think it is very important to point out that `$` is not a jQuery thing. It is used by jQuery...often. – John Greene Sep 14 '16 at 22:12

score 3 · Answer 2 · answered May 04 '12 at 06:03

No, you don't have to use the $ sign. It's just an aesthetic choice usually.

In your example code above, the function's argument is named form function (link, form). Inside the function, the new variable being declared has a $ to it so as to distinguish it from the argument variable form.

score 3 · Answer 3 · answered May 04 '12 at 06:05

3

That is not neccessary. The dollar sign before a variable is most of the times used as an indication it is a JQuery variable. JQuery uses the dollar sign as a shortcut. Using it in a variable name has no extra meaning other than the aesthetic meaning for the developer that it is a JQuery object.

answered May 04 '12 at 06:05

Rody

2,675
1
22
40

1

To clarify for others: The dollar sign *is* the variable. – Wesley Murch May 04 '12 at 06:05

score 0 · Answer 4 · answered May 04 '12 at 06:06

0

It has become best practice to use the $ sign to help you distinguish between Javascript variables representing regular DOM elements (and every other data type) and variables that hold a reference to a jQuery object. For the latter you use the $ sign.

answered May 04 '12 at 06:06

devnull69

16,402
8
50
61

Do I need to put a dollar before variable names with javascript?

4 Answers4

Linked