“javascript:void(0)” Fires window.onbeforeunload in IE

When Building a single page web application, we frequently provide a link as a trigger to run JavaScript.
 <a href = "javascript: void(0);" onclick = "alert('hello');" >Link</a>
When user clicks on the link, IE will  fires window.onbeforeunload event, although the link doesn't attempt to redirect to other page. This may make user annoyed. There are two solutions for this issue.
The first one is:
 <a href = "#" onclick = "alert('hello');" >Link</a>
The other one is :
 <a href = "javascript:;" onclick = "alert('hello'); return false;" >Link</a>

The  second one is preferred, since it will not append an anchor in URL.