Is there an "exists" function for jQuery

Question

So I know that you can do:

if ($(selector).length>0) {
    // Do something
}

But is there a more elegant method?

Answer 1

Yes!

jQuery.fn.exists = function(){return jQuery(this).length>0;}

if ($(selector).exists()) {
    // Do something
}

There you go!

This is in response to: Herding Code podcast with Jeff Atwood

Answer 2

You can use:

if ($(selector).is('*')) {
  // Do something
}

A little more elegant, perhaps.

Answer 3

if you used:

jQuery.fn.exists = function(){return ($(this).length > 0);}
if ($(selector).exists()) { }

you would imply that chaining was possible when it is not.

This would be better

jQuery.exists = function(selector) {return ($(selector).length > 0);}
if ($.exists(selector)) { }

EDIT

Just found this in the FAQ:

http://docs.jquery.com/Frequently_Asked_Questions#How_do_I_test_whether_an_element_exists.3F

if ( $('#myDiv').length ) { //do something }

EDIT 2

you could also use the following. If there are no values in the jQuery obj array then getting the first item in the array would return undefined.

if ( $('#myDiv')[0] ) { //do something }

Answer 4

if ( $('#myDiv').size() > 0 ) { //do something }

size() counts the number of elements returned by the selector

Answer 5

In JavaScript, everythig is truthy or falsy and for numbers, 0 means false, everything else true. So you could write:

if ($(selector).length)

and you don't need that "> 0" part.

Answer 6

I have found that sometimes .length throws an error, but [element locator].size() > 0 works reliably

Answer 7

.size() is deprecated.