:even Selector

even ( ) version added: 1.0

Description: Selects even elements, zero-indexed. See also odd.

In particular, note that the 0-based indexing means that, counter-intuitively, :even selects the first element, third element, and so on within the matched set.

Examples:

Example: Finds even table rows, matching the first, third and so on (index 0, 2, 4 etc.). 

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>css demo</title>

  <style>

  table {
    background: #eee;
  }

  </style>

  <script src="//code.jquery.com/jquery-1.10.2.js"></script>
</head>
<body>
  

<table border="1">
  <tr><td>Row with Index #0</td></tr>
  <tr><td>Row with Index #1</td></tr>
  <tr><td>Row with Index #2</td></tr>
  <tr><td>Row with Index #3</td></tr>
</table>

<script>

$( "tr:even" ).css( "background-color", "#bbf" );

</script>

  
</body>
</html>

Demo: