what does this mean in javascript?

[jemz]

Hi, I need some help on this, I saw a piece of code of javascript and i was confused on this,can you help me please or enlighten my mind,what does this javascript mean or how this behave.Thank you in advance.

this.className=this.className.replace(new RegExp(" over\\b"), "");

<!--[if lt IE 7]>
<script type="text/javascript">
sfHover = function() {
	var sfEls = document.getElementById("nav").getElementsByTagName("LI");
	for (var i=0; i<sfEls.length; i++) {
		sfEls[i].onmouseover=function() {
			this.className+=" over";
		}
		sfEls[i].onmouseout=function() {
			this.className=this.className.replace(new RegExp(" over\\b"), "");
		}
	}
}
if (window.attachEvent) window.attachEvent("onload", sfHover);
</script>
<![endif]-->

[Pullo]

This code adds :hover functionality to IE6 and below (as IE6 only supports the :hover pseudo-class on anchor tags).
In the line you ask about, "this" refers to a <li> element of an unordered list with the id "nav".
The script will apply a class of "over" to the <li> element in question when you mouse over it.
It will then remove the class as soon as you move your mouse away.

[Jason__C]

It means take the classname from "over" to empty. Meaning their would be no class for LI.

[jemz]

Hi, Thank you for the reply..what about this line

replace(new RegExp(" over\\b"), "");

why he uses the RegExp? and what does this

over\\b

mean?

[felgall]

The \\b is a regular expression code for a word boundary in that position it will match any whitespace character or the end of the text.

[jemz]

Hi felgall,thank you for the reply and for explaining me.