Question

for example,we have

<ul><li></li><li></li>....</ul>

we don’t know how many li tag in these code and right now i have a reference to one of these li elements.
is there a simple way to know if this reference is the last item?

Answer 1

You can use the :last-child selector, and check if the element matches it:

if( $('li').is(':last-child') ) {
    // ...
}

You should replace the 'li' selector above with your reference to the element.

Note that replacing it is necessary, since .is() will return true if any of the elements in the matched set matches the new selector, so you really only want to call it on your specific list-item.