jQuery官方的API這樣說明filter和find函式：

     filter(selector):
    Description: Reduce the set of matched elements to those that match the selector or pass the function’s test.

    find(selector):
    Description: Get the descendants of each element in the current set of matched elements, filtered by a selector. 
 

find()會在當前指定元素中查詢符合條件的子元素，是對它的子集操作，而filter()則是在當前指定的元素集合中查詢符合條件的元素，是對自身集合元素進行篩選。

看下邊的例子就會一目瞭然：

<div class="benben">
	<p>Hello,World!</p>
	<p>Hello,World Again!</p>
	<p class="test">Test1</p>
</div>
<div class="test">
	<p>Test2</p>
</div>
 

<script type="text/javascript">
//using find()
var $find=$("div").find(".test");
alert($find.html());//display "Test1"
//using test()
var $filter=$("div").filter(".test");
alert($filter.html());//display "Test2"
</script>

<script type="text/javascript">
$(document).ready(function() {
	//mouse hover
	$("ul.test>li").hover(function() {
		$(this).find("a:first").css({
			"background":"white",
			"position":"relative"
		});
	},
	//mouse out
	function(){
		$(this).find("a:first").css({
			"background":"",
			"position":""
		});
	});
});
</script>