.prevAll()

Categories: Traversing > Tree Traversal Chinese Translation: .prevAll()

.prevAll( [selector ] )Returns: jQuery

Description: Get all preceding siblings 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 .prevAll() method searches through the predecessors of these elements in the DOM tree and construct a new jQuery object from the matching elements; the elements are returned in order beginning with the closest sibling.

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:

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<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 elements which come before it:

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$( "li.third-item" ).prevAll().css( "background-color", "red" );

The result of this call is a red background behind items 1 and 2. Since we do not supply a selector expression, these preceding elements are unequivocally included as part of the object. If we had supplied one, the elements would be tested for a match before they were included.

Example:

Locate all the divs preceding the last div and give them a class.

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<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>prevAll demo</title>
  <style>
  div {
    width: 70px;
    height: 70px;
    background: #abc;
    border: 2px solid black;
    margin: 10px;
    float: left;
  }
  div.before {
    border-color: red;
  }
  </style>
  <script src="https://code.jquery.com/jquery-1.10.2.js"></script>
</head>
<body>
 
<div></div>
<div></div>
<div></div>
<div></div>
 
<script>
$( "div:last" ).prevAll().addClass( "before" );
</script>
 
</body>
</html>

Demo: