How do I test if an element with a certain ID exists on a page in jQuery?

Question

In jQuery, I have written a piece of code that appears on every page of my website.

var d = $('#someElement').offset().top;

However, not every page on my website has an element with an ID of "someElement". Unfortunately, on these pages that lack such an element, no jQuery code works.

To solve this problem, I want to test if an element on the page indeed has the ID of "someElement" and then only run the code snippet above if there is.

How do I perform this test? Will this test solve the problem? Thank you.

You might like to look at: http://stackoverflow.com/questions/31044/is-there-an-exists-function-for-jquery edit: in fact, this question is basically a duplicate of that one. Should it be marked as such? — Jeff, Jan 15 '12 at 23:49

score 8 · Accepted Answer · edited Jan 15 '12 at 23:46

8

$('#someElement').length will return 1 if the element exists, 0otherwise.

edited Jan 15 '12 at 23:46

jfriend00

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answered Jan 15 '12 at 23:44

Flo

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score 3 · Answer 2 · answered Jan 15 '12 at 23:44

3

Check the length of the jQuery object.

var element = $('#someElement');
if (element.length) {
    var element_top = element.offset().top;
}

answered Jan 15 '12 at 23:44

Quentin

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score 1 · Answer 3 · edited Jan 15 '12 at 23:46

1

Use if statemtent: if ($('#someElement').length) { do something }

edited Jan 15 '12 at 23:46

jfriend00

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answered Jan 15 '12 at 23:45

Adaz

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score 1 · Answer 4 · answered Jan 15 '12 at 23:45

1

try this:

if($('#someElement').length>0){
   var d = $('#someElement').offset().top;
}

answered Jan 15 '12 at 23:45

falinsky

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score 1 · Answer 5 · answered Jan 15 '12 at 23:50

1

Just an alternative way of solving it: You can run var d = $('#someElement').offset() without causing an error (it will just return null), even if the element does not exist. So try:

var d = $('#someElement').offset();
if (d) {
    d = d.top;
}

answered Jan 15 '12 at 23:50

David Hellsing

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score 1 · Answer 6 · edited Mar 13 '13 at 02:00

1

Do not use jQuery for that! Use getElementById, since if the element is not in the DOM, the result will be null.

if (document.getElementById("someElement")) {

}

edited Mar 13 '13 at 02:00

phs

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answered Jan 16 '12 at 05:38

Garrett

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How do I test if an element with a certain ID exists on a page in jQuery?

6 Answers6