jQuery prev() 方法用于获取同级兄弟节点的上一个元素。此方法与 DOM 元素的前一个兄弟元素一起向后遍历。

语法

selector.prev( selector )
selector：可选参数，该参数用于指定一个选择器表达式，以缩小对前一个兄弟的搜索范围。

例子

例1 

找到p元素的上一个元素是h2元素。

<!DOCTYPE html>
<html>
<head>
<style>
.main * {
	display: block;
	font-size: 20px;
	position: relative;
	border: 2px solid black;
	color: black;
	padding: 10px;
	margin: 17px;
}
</style>
<script src="https://code.jquery.com/jquery-3.5.1.min.js"></script>
<script>
function fun(){
	$(document).ready(function(){
	    $("p").prev().css({ "font-size": "30px", "color": "blue", "border": "6px dashed blue"});
	});
}
</script>
</head>

<body class = "main"> body
<div id = "div1"> div 
<ul> ul  </ul>
<h2>  h2 </h2>
<p>  p </p>
</div>
<button onclick = "fun()"> 点击看看 </button>
</body>
</html>

例2

<!DOCTYPE html>
<html>
<head>
<style>
.main * { 
  display: block;
  font-size: 20px;
  position: relative;
  border: 2px solid black;
  color: black; 
  padding: 10px;
  margin: 17px;
}
</style>
<script src="https://code.jquery.com/jquery-3.5.1.min.js"></script>
<script>
function fun(){
$(document).ready(function(){
  $("h2").prev("p").css({ "color": "blue", "border": "5px dashed blue"});
});
}
</script>
</head>
<body class = "main"> body
<div id = "div1"> div 
<ul> ul  </ul>
<h2>  h2 </h2>
<p> p </p>
<h2>  h2 </h2>
<span> span  </span>
<h2>  h2 </h2>
</div>
<button onclick = "fun()"> 点击看看 </button>
</body>
</html>

例3

循环查找上一个元素

<!DOCTYPE html>
<html>
<head>
<style>
div { 
  display: block;
  width: 50px;
  height: 50px;
  font-size: 20px;
  margin: 10px;
  border: 2px solid black;
  float: left;
}
p {
	clear: left;
	margin: 10px;
}
</style>
<script src = "https://code.jquery.com/jquery-3.5.1.min.js"> </script>
<script>
$(document).ready(function(){
	var current = $("#d5");
	current.css( "background-color", "red");
	$("button").click(function(){
	  current  = current .prev();
	  $("div").css("background", "");
	  current.css( "background-color", "red" );
	});
});
</script>
</head>

<body>
<div> </div>
<div> </div>
<div> </div>
<div> </div>
<div id = "d5"> </div>
<p> 点击下面的按钮查看效果。 </p>
<p>
<button> 点击看看 </button>
</p>
</body>

</html>
jQuery prev() 方法