jquery 简易menu

<ul id="menu" style="width:300px;background-color:yellow">
	<li><a style="width:100px;background-color:pink" href="#">1</a>
		<ul>
			<li style="background-color:red">1</li>
			<li style="background-color:red">2</li>
			<li style="background-color:red">3</li>
		</ul>
	</li>
	
	<li><a style="width:100px;background-color:pink" href="#">2</a>
		<ul>
			<li style="background-color:red">1</li>
			<li style="background-color:red">2</li>
			<li style="background-color:red">3</li>
		</ul>
	</li>
	
	<li><a style="width:100px;background-color:pink" href="#">3</a>
		<ul>
			<li style="background-color:red">1</li>
			<li style="background-color:red">2</li>
			<li style="background-color:red">3</li>
		</ul>
	</li>
</ul>

<script type="text/javascript" src="/common/js/jquery-1.4.2.min.js"></script>
<script type="text/javascript">	
	$(document).ready(function() {
		$("#menu > li > ul").css("display","none");
		
		$("#menu > li").click(function(event){
			if(event.target===this||event.srcElement===this){
				if($(this).children("ul").css("display")==="block"){
					$(this).children("ul").css("display","none");
				}else{
					$("#menu > li > ul").css("display","none");
					$(this).children("ul").css("display","block");
				}
				
			}
		});
	});
</script>

如果不使用event.target===this(FF) || event.srcElement===this(IE)的判断，则在点下级li时也会将menu隐藏掉，刚开始在这个问题上有些困惑，现在终于解决了。