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Basic introduction and example demonstration of first() selector in jQuery
- 巴扎黑Original
- 2017-06-22 15:23:311341browse
Definition and Usage
first() Reduces the set of matching elements to the first element in the set.
Syntax
.first()
Detailed description
If given a jQuery object that represents a collection of DOM elements, .first() Method will construct a new jQuery object with the first matching element.
Consider the following page with a simple list:
<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> </ul>
We can apply this method to this collection of list items:
$('li').first().css('background-color', 'red');
Example display:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>:first选择器</title>
<script type="text/javascript" src="jquery-2.0.3.js"></script>
<style type="text/css">
body{
width:7%;
height:100%;
font-size:24px;
font-weight:bold;
background-color:#CCCCFF;
text-align:center;
}
</style>
<script type="text/javascript">
$(function(){
//设置ul中的第一个li的背景色，运用到:first选择器
$("li:first").css("background-color","#00DDDD");
//设置ol中的第一个li的背景色，运用到:first选择器
$(".two li:first").css("background-color","#0000CC");
//设置ol中的第一个li的字体颜色，运用到:first选择器
$(".two li:first").css("color","#FFFFFF");
});
</script>
</head>
<body>
<div>
<ul class="one">
<li>苹果</li>
<li>梨子</li>
<li>橘子</li>
<li>西瓜</li>
<li>荔枝</li>
<li>葡萄</li>
<li>香蕉</li>
<li>香瓜</li>
</ul>
<ol class="two">
<li>苹果</li>
<li>梨子</li>
<li>橘子</li>
<li>西瓜</li>
<li>荔枝</li>
<li>葡萄</li>
<li>香蕉</li>
<li>香瓜</li>
</ol>
</div>
</body>
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