web前端页面中异步使用百度地图API

<div id="allmap"></div>

 //百度地图API功能
 function loadJScript() {
 var script = document.createElement("script");
 script.type = "text/javascript";
 script.src = "http://api.map.baidu.com/api?v=2.0&ak=8ni9BKv4NW6uDu5LUrRKCuCGp4RREX3g&callback=init";
 document.body.appendChild(script);
 }

 function init() {
 var map = new BMap.Map("allmap"); // 创建Map实例
 var point = new BMap.Point(116.293088,39.830886); // 创建点坐标
 map.centerAndZoom(point, 18);
 map.enableScrollWheelZoom(); //启用滚轮放大缩小
 var marker = new BMap.Marker(point);
 map.addOverlay(marker); // 将标注添加到地图中
 marker.setAnimation(BMAP_ANIMATION_BOUNCE); //跳动的动画

 }
 window.onload = loadJScript; //异步加载地图