Hey, this is a very simplified version of a Dashboard script I'm writing. I'm new to using objects, so I'm missing something here. I'm trying to figure out why inside download.start() the object variable "this.size" calls the right number, but in download.done(), it's coming up as undefined. Any help?

var download = {
	size : null,
	
	start : function(startSize) {
		this.size = startSize;
		setTimeout(this.done, 2000);
		alert("The Size is: " + this.size);
	},
	
	done : function() {
		alert("Now, the Size is: " + this.size);
	}
}

window.onload = function() {
	download.start(10);
}

EDIT - figured it out : setTimeout("download.done()", 2000); b/c when called the "this" is referring the window.

Very interesting problem. I honestly can't explain the behavior but, changing the inner function 'done' to

    done : function() {
        alert("Now, the Size is: " + download.size);
    }

will make it do what is expected.

If you don't mind, I'd like to post this on the 'comp.lang.javascript' newsgroup. There are some folks there that know js inside and out.

Ok, here is the answer.
the value of 'this' changes in the second method call.
When you do this:

 setTimeout(this.done, 2000);

the 'done' function is being called as part of the 'window' object instead of the download object. In this context, 'this' refers to the 'window' object.

However, if you change the timeout to this:

 setTimeout("download.done()", 2000);

Then, the 'this' object in the 'done' function will refer to the download object.

I hope that makes sense

You didn't create an object to refer to with "this". Those are "static methods" if you want to make an analogy with traditional OOP.