Comparing variable to empty jquery object in if condition

Question

In the jQuery accordion API, it says "If the accordion is collapsing, ui.newHeader and ui.newPanel will be empty jQuery objects."

How can I check if ui.newheader is an empty jQuery object? I've tried it like this:

if ($(ui.newHeader) == null)
{
    ...
}

,like this:

if (ui.newHeader == null)
{
    ...
}

and this:

if ($(ui.newHeader) == "")
{
    ...
}

So basically, this is a question about jquery/javascript syntax :) Thanks

It's not really a syntax question - all three of the things you tried are valid JavaScript syntax, they just don't do what you want to do. — nnnnnn, Jun 29 '13 at 12:38

score 5 · Accepted Answer · answered Jun 29 '13 at 12:20

5

What you want is to know if there is 0 element in the set. Do it like this :

if ($(ui.newHeader).length==0) {

answered Jun 29 '13 at 12:20

Denys Séguret

score 1 · Answer 2 · answered Jun 29 '13 at 12:22

1

if (!$(ui.newHeader).length)

or

if (!$(ui.newHeader)[0])

answered Jun 29 '13 at 12:22

A. Wolff

score 1 · Answer 3 · answered Jun 29 '13 at 12:24

1

jQuery object is array like collection. So, it is empty means, it's length property is 0.

if(!$(ui.newHeader).length) {...}

answered Jun 29 '13 at 12:24

3 Answers3