.has()

Categories: Traversing > Filtering Chinese Translation: .has()

.has( selector )Returns: jQuery

Description: Reduce the set of matched elements to those that have a descendant that matches the selector or DOM element.

Given a jQuery object that represents a set of DOM elements, the .has() method constructs a new jQuery object from a subset of the matching elements. The supplied selector is tested against the descendants of the matching elements; the element will be included in the result if any of its descendant elements matches the selector.

Consider a page with a nested list as follows:

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 <ul>
  <li>list item 1</li>
  <li>list item 2
    <ul>
      <li>list item 2-a</li>
      <li>list item 2-b</li>
    </ul>
  </li>
  <li>list item 3</li>
  <li>list item 4</li>
</ul>

We can apply this method to the set of list items as follows:

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$( "li" ).has( "ul" ).css( "background-color", "red" );

The result of this call is a red background for item 2, as it is the only <li> that has a <ul> among its descendants.

Example:

Check if an element is inside another.

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<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>has demo</title>
  <style>
  .full {
    border: 1px solid red;
  }
  </style>
  <script src="https://code.jquery.com/jquery-1.10.2.js"></script>
</head>
<body>
 
<ul><li>Does the UL contain an LI?</li></ul>
 
<script>
$( "ul" ).append( "<li>" +
  ( $( "ul" ).has( "li" ).length ? "Yes" : "No" ) +
  "</li>" );
$( "ul" ).has( "li" ).addClass( "full" );
</script>
 
</body>
</html>

Demo: