Someone

<script>
var dblClick=false;

function drop_dblClick() {
	dblClick=false;
}

function set_dblClick() {
	if (dblClick) {
		alert('double clicked!');
	}
	dblClick=true;
	setTimeout('drop_dblClick()',200);
}
</script>
<div onclick="set_dblClick();">click me!</div>