jquery filter方法

<ul>
  <li>list item 1</li>
  <li>list item 2</li>
  <li>list item 3</li>
  <li>list item 4</li>
  <li>list item 5</li>
  <li>list item 6</li>
</ul>


<script>...
$('li').filter(':even').css('background-color', 'red');
</script>

		

<script>...
$(document).ready(function()...{
  $("p").filter(".intro,#outro").css("background-color","yellow");
});
</script>

<h1>Welcome to My Homepage</h1>
<p>My name is Donald.</p>
<p class="intro">I live in Duckburg.</p>
<p id="outro">I love Duckburg.</p>
<p>My best friend is Mickey.</p>

		

<script>...
$(document).ready(function()...{
 $("p").filter($("li p.intro")).css("background-color","yellow");
});
</script>

<li style="border:1px solid black;">
This is a li element
<h1>Welcome to My Homepage</h1>
<p>My name is Donald.</p>
<p class="intro">I live in Duckburg (will be selected).</p>
<p>My best friend is Mickey.</p>
</li>

<p class="intro">This p element is outside the li element.</p>
<p>This p element is also outside the li element.</p>

		

<script>...
$(document).ready(function()...{
  $("p").filter(function()...{  
    return $("span",this).length==2;}).css("background-color","yellow");
});
</script>

<li>
<p>A p element <span>with one span element.</span></p>
<p>A p element <span>with</span> two <span>span elements.</span></p>
<p>A p element <span>with one span element.</span></p>
<p>A p element <span>with</span> two <span>span elements.</span></p>
<p>A p element with no span element.</p>
</li>

<p>This example returns all p elements that have two span elements. P elements with none, one, or more than two span elements, will not be returned.</p>