Jquery: can you explain this line of code to me? help me to understand it, or give references to where I can learn about it

Jquery 1.6 just came out, I grabbed this code from the .is api page. I j开发者_JAVA百科ust had a few questions on a piece of code I saw there:

1) why is return needed? Isn't there another way to write this that's easier? I mean, i've never used return when I've written anything Jquery. Obviously I haven't written anything advanced and i'm still just learning. Why would you need it, when would you use it? and is there another way to do the same thing?

2) $('strong', this) means "any <strong> elements in this element." right? and that full line would read "give me the element that has 2 strong elements within this"? right? or? (i think i have that wrong.) isn't there another way to write this? i've only seen this used a few times.

$("li").click(function() {   
var $li = $(this),
    isWithTwo = $li.is(function() {

      return $('strong', this).length === 2;

    });   
if ( isWithTwo ) {
    $li.css("background-color", "green");   } else {
    $li.css("background-color", "red");   } });

why is return needed?

Look at the documentation for is. The point is that the function will return either true or false.

$('strong', this) means "any <strong> elements in this element." right?

yes

and that full line would read "give me the element that has 2 strong elements within this"?

No. It will be "If there are 2 strong elements, return true, otherwise return false"

return $('strong', this).length === 2;

If this has 2 <strong> elements, return true. Otherwise, return false.