<!DOCTYPE html>
<html>
<head>
<script>
function initialize()
{
  var mapProp = {
    center: new google.maps.LatLng(51.508742,-0.120850),
    zoom:7,
    mapTypeId: google.maps.MapTypeId.ROADMAP
  };
  var map = new google.maps.Map(document.getElementById("googleMap"),mapProp);
}

function loadScript()
{
  var script = document.createElement("script");
  script.type = "text/javascript";
  script.src = "http://maps.googleapis.com/maps/api/js?key=AIzaSyDY0kkJiTPVd2U7aTOAwhc9ySH6oHxOIYM&sensor=false&callback=initialize";
  document.body.appendChild(script);
}

window.onload = loadScript;
</script>
</head>

<body>
<div id="googleMap" style="width:500px;height:500px;"></div>

</body>
</html>