返回值:jQueryprev([selector])

Get the immediately preceding sibling of each element in the set of matched elements, optionally filtered by a selector.

Given a jQuery object that represents a set of DOM elements, the .prev() method allows us to search through the predecessors of these elements in the DOM tree and construct a new jQuery object from the matching elements.

The method optionally accepts a selector expression of the same type that we can pass to the $() function. If the selector is supplied, the elements will be filtered by testing whether they match it.

Consider a page with a simple list on it:

<ul>
   <li>list item 1</li>
   <li>list item 2</li>
   <li class="third-item">list item 3</li>
   <li>list item 4</li>
   <li>list item 5</li>
</ul>

If we begin at the third item, we can find the element which comes just before it:

$('li.third-item').prev().css('background-color', 'red');

The result of this call is a red background behind item 2. Since we do not supply a selector expression, this preceding element is unequivocally included as part of the object. If we had supplied one, the element would be tested for a match before it was included.

示例:

Find the very previous sibling of each div.

<!DOCTYPE html>
<html>
<head>
<style>
  div { width:40px; height:40px; margin:10px;
        float:left; border:2px blue solid; 
        padding:2px; }
  span { font-size:14px; }
  p { clear:left; margin:10px; }
  </style>
<script src="jquery.min.js"></script>
</head>
<body>

<div></div>
  <div></div>
  <div><span>has child</span></div>

  <div></div>
  <div></div>
  <div></div>
  <div id="start"></div>

  <div></div>
  <p><button>Go to Prev</button></p>

<script>


    var $curr = $("#start");
    $curr.css("background", "#f99");
    $("button").click(function () {
      $curr = $curr.prev();
      $("div").css("background", "");
      $curr.css("background", "#f99");
    });



</script>
</body>
</html>
演示:

示例:

For each paragraph, find the very previous sibling that has a class "selected".

<!DOCTYPE html>
<html>
<head>
<script src="jquery.min.js"></script>
</head>
<body>

<div><span>Hello</span></div>

  <p class="selected">Hello Again</p>
  <p>And Again</p>

<script>

$("p").prev(".selected").css("background", "yellow");

</script>
</body>
</html>
演示: