Checking if a jQuery selector doesn't find any results

Question

I'm used to Prototypejs, where $$("selector") will return null if no elements were found. This is convenient because I can do

if ($$("selector")) {}

to check if an element is in the DOM.

However, in jQuery $(selector) will return [] if no element is found, so now I need to do:

if ( $(selector).length > 0 )

This makes code slightly harder to read.

My question: What's the best way of doing this? Should I extend the jQuery object with methods like .empty() and .any(), or are there built in functions to do this?

Update: This also applies to other selectors on jQuery which should, anyways, only return one result (like parent(), or closest())

You only need to do `if ($(selector).length)` since it seems the `0` is falsey... — David Thomas, Aug 21 '11 at 21:38

score 47 · Accepted Answer · answered Aug 21 '11 at 21:39

47

$.fn.exists = function () {
    return this.length !== 0;
}

Used like:

$("#notAnElement").exists();

answered Aug 21 '11 at 21:39

Baz1nga

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idk if it's faster or if it matters, but you could use `$.fn.exists = function () { return !!this[0]; }` too – Joseph Marikle Aug 21 '11 at 23:04

score 23 · Answer 2 · answered Aug 21 '11 at 21:38

23

Using length is the best way. You shouldn't use empty() or size() > 0 since that just adds another entry to the call stack.

answered Aug 21 '11 at 21:38

Chris Laplante

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Using if ($(select).length) works quite well, I forgot that I could omit the > 0! – micho Aug 21 '11 at 22:17

score 12 · Answer 3 · answered Aug 21 '11 at 21:39

12

if ( $(selector)[0] )

That'll do it.

answered Aug 21 '11 at 21:39

Joseph Marikle

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Checking if a jQuery selector doesn't find any results

3 Answers3