.tooltip() is not a function

I got rid of the error by adding the boostrap libs & css

<link rel="stylesheet" type="text/css" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/css/bootstrap.min.css" />

<script type="text/javascript" src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/js/bootstrap.min.js"></script>

Try doing something like this. For tooltip to work, you will require title set for the control.

HTML

<td id="bookingTd" title="This is a tooltip." 
     class="<%= booking.status %>" 
     onclick='$("#booking<%= booking.id %>").dialog()'>

</td>

JavaScript

$(document).ready(function(){
   $("#bookingTd").tooltip();
});

Also make sure you load jQuery first and then the tooltip plugin.

Hope this helps you.