If your onclick function returns false the default browser behaviour is cancelled. As such:
<a href="http://www.google.com" onclick='return check()'>check</a>
<script type="text/javascript">
function check()
{
return false;
}
</script>
Either way, whether google does it or not isn’t of much importance. It’s cleaner to bind your onclick functions within javascript – this way you separate your HTML from other code.