.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.
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version added: 1.4.has( selector )
selectorA string containing a selector expression to match elements against.
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version added: 1.4.has( contained )
containedA DOM element to match elements against.
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:
<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:
$('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.
<!DOCTYPE html>
<html>
<head>
<style>
.full { border: 1px solid red; }
</style>
<script src="http://code.jquery.com/jquery-1.7rc2.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>