.index()- returns an integer indicating the position of the passed element relative to the original collection.-1 means selector or element not found.
Three way to use index()
1.index()
2..index( selector )
selector A selector representing a jQuery collection in which to look for an element.
3..index( element )
element The DOM element or first element within the jQuery object to look for.
Note : Start index is 0(Zero).
more detail- http://api.jquery.com/index
Example
<html>
<head>
<style>div { font-weight: bold; color: #090; }</style>
<script src="http://code.jquery.com/jquery-latest.js"></script>
</head>
<body>
<ul>
<li id="foo">foo</li>
<li id="bar">bar</li>
<li id="baz">baz</li>
</ul>
<div></div>
<script> var listItem = $('#bar');
$('div').html( 'Index: ' + $('li').index(listItem) ); </script>
</body>
</html> - foo
- bar
- baz
Index: 1
