.eq()

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

.eq( index )Returns: jQuery

Description: Reduce the set of matched elements to the one at the specified index.

  • version added: 1.1.2.eq( index )

    • index
      Type: Integer
      An integer indicating the 0-based position of the element.

  • version added: 1.4.eq( indexFromEnd )

    • indexFromEnd
      Type: Integer
      An integer indicating the position of the element, counting backwards from the last element in the set.

Given a jQuery object that represents a set of DOM elements, the .eq() method constructs a new jQuery object from one element within that set. The supplied index identifies the position of this element in the set.

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>list item 3</li>
  <li>list item 4</li>
  <li>list item 5</li>
</ul>

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

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$( "li" ).eq( 2 ).css( "background-color", "red" );

The result of this call is a red background for item 3. Note that the supplied index is zero-based, and refers to the position of the element within the jQuery object, not within the DOM tree.

Providing a negative number indicates a position starting from the end of the set, rather than the beginning. For example:

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$( "li" ).eq( -2 ).css( "background-color", "red" );

This time list item 4 is turned red, since it is two from the end of the set.

If an element cannot be found at the specified zero-based index, the method constructs a new jQuery object with an empty set and a length property of 0.

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$( "li" ).eq( 5 ).css( "background-color", "red" );

Here, none of the list items is turned red, since .eq( 5 ) indicates the sixth of five list items.

Example:

Turn the div with index 2 blue by adding an appropriate class.

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<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>eq demo</title>
  <style>
  div {
    width: 60px;
    height: 60px;
    margin: 10px;
    float: left;
    border: 2px solid blue;
  }
  .blue {
    background: blue;
  }
  </style>
  <script src="https://code.jquery.com/jquery-1.10.2.js"></script>
</head>
<body>
 
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
 
<script>
$( "body" ).find( "div" ).eq( 2 ).addClass( "blue" );
</script>
 
</body>
</html>

Demo: