【百度地图API】让用户选择起点和终点的驾车导航

<script type="text/javascript">
	// 百度地图API功能
	var map = new BMap.Map("allmap");
	map.centerAndZoom(new BMap.Point(116.404, 39.915), 11);
	//三种驾车策略：最少时间，最短距离，避开高速
	var routePolicy = [BMAP_DRIVING_POLICY_LEAST_TIME,BMAP_DRIVING_POLICY_LEAST_DISTANCE,BMAP_DRIVING_POLICY_AVOID_HIGHWAYS];
	$("#result").click(function(){
      var start = document.getElementById("startPosition").value;//起始点
      var end = document.getElementById("endPosition").value;//终止点
		map.clearOverlays(); 
		var i=$("#driving_way select").val();
		search(start,end,routePolicy[i]); 
		function search(start,end,route){ 
			var driving = new BMap.DrivingRoute(map, {renderOptions:{map: map, autoViewport: true,enableDragging : true},policy: route});
			driving.search(start,end);
		}
	});
</script>

　　解决方案就是将变量的声明放在function函数里面。（前提：body处创建两个input）

var start = document.getElementById("startPosition").value;//起始点
      var end = document.getElementById("endPosition").value;//终止点