Why is $(document).ready not firing for me?

In a php file i have used include to include the following js.php file and prior to that i have included the jquery file.

<script type="text/javascript">

$(document).ready(function(){
     alert("hello");
});
</script>

But it doesn’t work. Why? when I skip the $(document).ready function it works.

But i need jquery code inside. what is wrong?

Answer

The most likely answer, based on what you have said, is that the core jQuery file is not actually included correctly in the page. You need something like:

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>

Chances are, this is missing or typed incorrectly.