uncaught referenceerror $ is not defined in js code example

Example 1: $ is not defined

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js" type="text/javascript"></script>

Example 2: $ not defined error

<script src="http://ajax.googleapis.com/ajax/libs/jquery/2.0.0/jquery.min.js"></script>
<script type="text/javascript" src="./javascript.js"></script>
<script
    src="http://maps.googleapis.com/maps/api/js?key=YOUR_APIKEY&sensor=false">
</script>