Question

In the example of jQuery’s find()
(the doc is at http://api.jquery.com/find/)

I wonder why we need it, because, is

$('li.item-ii').find('li')

the same as

$('li.item-ii li')

essentially, all the <li> elements inside the <li> element that has the class item-ii

Similarly

$('#id1').find(".class1 #id2")

is the same as

$('#id1 .class1 #id2")

?

Update: if they are the same, why do we need find() ? is it because mainly when we need to further select some elements when given another element in a variable, so we can do elementFoo.find("...")?

Answer 1

Yes, these are equivalent. The result is the same, it’s called the descendant selector. Their utility differs a little bit (e.g. using .end(), .andSelf(), etc), but for just selecting elements, you’re finding the same set.

For kicks, you can also do this:

$('li', 'li.item-ii')

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For your edit: Why do we need it? Sometimes you’re not coming from a selector, quick example:

$(this).find('.childElementClass')

There are many times you need to find something relatively, not from a known selector (could be a DOM element, this, an iframe document, etc). There are many other traversal functions for this as well.