uncaught referenceerror is not defined in javascript code example

Example 1: reference error $ is not defined jquery

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>

Example 2: register:48 Uncaught ReferenceError: $ is not defined

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>