Question

I am trying to use this code to display some data when the mouse is over that link:

<span  id="ssd" onmouseover="this.T_WIDTH=210;this.T_TITLE='(0/0) mqe= ';"><a href='http://en.wikipedia.org/wiki/Decision_tree_learning'>http://en.wikipedia.org/wiki/Decision_tree_learning</a></span><br/>

Do you see something wrong because I can’t make it work.

Answer 1

Let’s get away from this DOM level 0 stuff:

var spSsd = document.getElementById("ssd");
spSsd.addEventListener("mouseover", function () {
     this.style.width = "240px";
     this.setAttribute("title", "(0/0) mqe");
});

I assume your this.T_WIDTH=210 was supposed to set the width of the span, and this.T_TITLE=(0/0) mqe was supposed to set the title? The code above should do that, just note that you need to set your span to display:block for this to work, since inline elements don’t really have a width.

Just make sure you put this script at the bottom of your body; executing it in the head will give you a null error, since the span ssd will not have been created yet. Or if you’re using jQuery, you could put it in the document.ready function.