When a link is clicked it takes the user to the page specified in the URL of the HREF attribute. To prevent this from happening, use javascript:void(0) as the value of HREF.
<A HREF="javascript:void(0)" onmouseover="document.bgColor='#EEEEEE'"> Dead link</A>
You may wonder why we can’t use HREF=”” (a blank or no value) instead of HREF=”javascript:void(0)”. The reason is that a blank or null value for HREF is interpreted as the URL of the directory. Thus, in our case if we use HREF=””, the browser actually sees it as http://www.webdevelopersnotes.com/tutorials/javascript/.
javascript:void(0) returns (not specifies!) a null value. Hence, whenever a link is clicked no page is loaded.
Mouse clicks and event handlers
So far we have only looked at event handlers that capture mouse movements over a link. JavaScript also provides event handlers for links that understand mouse button clicks; onclick and ondblclick. Their usage is similar to other event handlers.
<A HREF="javascript:void(0)" onclick="alert('You clicked on the link')"> Dead link</A>
<A HREF="javascript:void(0)" ondblclick="alert('You double clicked on the link')"> Double click on me</A>