How does jQuery act on multiple selectors?

I've been wondering for a little while how jQuery acts on multiple selectors. For instance:

$("p").css({"border":"1px solid #000"});

Performs the subsequent function on all p tags. I've had a look through the jQuery source but to be honest it's an extensive read when you're trying to work out one specific bit of functionality. My assumption is that there's some kind of stack whereby css() and other functions merely act on the current stack, which is divined by the selector function.

Other than that, I can't work out how it could be replicated as, I think, there's no way in javascript to return multiple objects to execute a function on. E.g.

House.first_bedroom.size开发者_如何学编程 = "large"
House.second_bedroom.size = "small"
House.all_rooms().alertSize();

alertSize() would have to be a member function of some collection of objects rather than a member function of each room object that is returned by all_rooms()?

First, jQuery functions (generally) return a jQuery object, which acts like an array and keeps track of the current set of matched elements. Second, internally each jQuery function makes extensive use of the each() function to iterate over the matched objects, perform subsequent actions and construct the new jQuery object to return. Some functions do return something other than jQuery, like get(). These functions cannot be chained. Chaining is only possible when the function returns a jQuery object. Because the returned object is a jQuery object it has all the functions of jQuery available to it.

The jquery constructor ($(...)) always return a jquery object. You can think of it as a fancy array. The items selected are stored (looks like this is called context in the source).

So then on your object you're calling the function css... See jQuery.fn.css in the source. It basically calls a function which performs the delegate (setting or getting the css) on each item in the context.

Perhaps the DOM is parsed and all elements matching the criteria are added to an array? Or.. something more efficient? :)

Similarly, for event handling, a handler is assigned to each element in the array?

I'm just stabbing in the dark here.