I use the following code for my website but it does not work. What is the problem? I've included the snippet for error reporting.
 <head>
 <script src="http://maps.googleapis.com/maps/api/js?sensor=false&libraries=places" type="text/javascript">
</script>
    <script type="text/javascript">
        function initialize() {
            var options = {
                types: ['(cities)'],
                componentRestrictions: {country: "us"}
            };
            var input = document.getElementById('searchTextField');
            var autocomplete = new google.maps.places.Autocomplete(input , options);
        }
        google.maps.event.addDomListener(window, 'load', initialize);
    </script>
</head>
<body>
    <div class = "row">
        <input id="searchTextField" type="text" size="50" placeholder="Enter a location" autocomplete="on">
    </div>
    </body>