Jquery - $(selector).scroll is passing parameters to its callback function?

Question

i was reading those few lines of code from a javascript(Jquery) file and I was wondering where those arguments "x" and "y" are coming from.Is the scroll event that is taking care peraphs?

$(window).scroll(function(x,y) {

        dosomething(withThis);
    });

thanks Luca

PS here is the jquery excerpt that made me ask this question Is this an elegant way to make elements fade in while scrolling?

Answer 1

Well, open Firebug console (or web dev. tools) and paste there this code:

 $(window).scroll(function(x,y,z) {
    console.log(x,y,z)
 });

After execution and scrolling you'll see the result (works on sites with jQuery).

As expected, first argument - event object, 2nd and 3rd - undefined;

But, you can trigger events manually, and pass any arguments.

More info here: http://api.jquery.com/trigger/

Answer 2

No, the handler for the scroll event takes only an event object, not x,y . That code is misleading and wrong. We can't help if you don't show the full code.

This is the same thing as if you define a method

function add(a,b) {
   return a + b;
}

// When called like this, b will be undefined, as is y in your example
// programmer error not caught by the compiler
add(7);

Answer 3

You could inspect the arguments variable on any function, so you can get an idea of the data that's passed in.

$(window).scroll(function() {
    console.log(arguments);
});