Classic javascript qestion

[katz_tomas]

Whats the difference between:
1) thisImage.onmouseover = rollOver
2)thisImage.onmouseover = rollOver()

I used option (2) and I got an Error saying:
TypeError: this.outImage is undefined
[Break On This Error]
this.src = this.outImage.src;

---------------THE FULL SCRIPT IS BELOW the one that didn't work----------------

window.onload = rolloverInit;

function rolloverInit() {
for (var i=0; i<document.images.length; i++) {
if (document.images[i].parentNode.tagName == "A") {
setupRollover(document.images[i]);
}
}
}

function setupRollover(thisImage) {
thisImage.outImage = new Image();
thisImage.outImage.src = thisImage.src;
thisImage.onmouseout = rollOut();

thisImage.overImage = new Image();
thisImage.overImage.src = "images/" + thisImage.id + "_on.gif";
thisImage.onmouseover = rollOver();
}

function rollOut() {
this.src = this.outImage.src;
}

function rollOver() {
this.src = this.overImage.src;
}
-----------THANKS AT ADVANCE---------------

[xelawho]

"this" is quite a powerful keyword in javascript, and you have to be careful which object it is referring to. used in a function it can refer to the function itself or the window object.

I'¡m not sure I follow your code, but I think it would be safer to do it something like this:

thisImage.onmouseover = rollOver(thisImage);

function rollOver(pic) {
pic.src = pic.overImage.src;
}