Java EE (Java Enterprise Edition) General Discussion

<SELECT onchange="window.location.href=this.options
    [this.selectedIndex].value">
<OPTION VALUE="http://www.microsoft.com/ie">
    Internet Explorer</OPTION>
<OPTION VALUE="http://www.microsoft.com">
    Microsoft Home</OPTION>
<OPTION VALUE="http://msdn.microsoft.com">
    Developer Network</OPTION>
</SELECT>

When I choose one of the options in this drop/down list I understand that "onchange" gets "fired".

I thought that selectedIndex took an argument corresponding to the option in the list (selectedIndex(2) is the second option in the drop/down-list). But here "this" is used in front of selectedIndex. Hope someone can explain.