谷歌地图api不加载地图

我正在使用此代码来生成谷歌地图使用谷歌地图API。这是工作示例jsfiddle 谷歌地图api不加载地图

js代码

<script src="https://maps.googleapis.com/maps/api/js?v=3.exp"></script> 

function initialize() { 
    var myloc = new google.maps.LatLng(35.433820, -97.135620); 
    var mapOptions = { 
     zoom: 17, 
     topCenter: myloc, 
     scrollwheel: false 
    }; 
    var map = new google.maps.Map(document.getElementById('map'),mapOptions); 
    var marker = new google.maps.Marker({ 
     position: map.getCenter(), 
     map: map, 
     animation: google.maps.Animation.BOUNCE 
    }); 
    var contentString = '<div id="content" style="dir:rtl; text-align:right;">'+ 
      '<div id="siteNotice">'+ 
      '</div>'+ 
      '<h1 id="firstHeading" class="firstHeading"><h1>title here</h1>'+ 
      '<div id="bodyContent">'+ 
      '<p>description here</p>'+ 
      '</div>'+ 
      '</div>'; 
    var infowindow = new google.maps.InfoWindow({ 
     content: contentString, 
     maxWidth: 250 
    }); 
    google.maps.event.addListener(marker, 'click', function() { 
     infowindow.open(map,marker); 
    }); 
} 
google.maps.event.addDomListener(window, 'load', initialize);

HTML代码