arcgis js 通用分屏

1、arcgis js 分屏进行了优化，适用于任何多个屏幕分屏

2、合理应用map的销毁事件

 var mapht = new HashTable();
    function drop(ev) {
        var mapdivId = ev.target.id;
        var mapId = ev.target.id;
        var data = ev.dataTransfer.getData("Text");
      
        ev.preventDefault();
        var url = Name_Layer_obj.getValue(data)["url"];
        
        if (mapdivId.indexOf("_gc") > 0) {
            var maptarget = ev.target;
            mapId=mapdivId.substring(0,mapdivId.indexOf("_gc"));
            var map = mapht.getValue(mapId);
            map.destroy();
        }

        var map1 = new esri.Map(mapId, {
            logo: false,
            nav: false,
            slider: false,
            zoom: 3,
            isDoubleClickZoom: false,
        });
        if (mapht.containsKey(mapId)) {
            mapht.remove(mapId);
        }
        mapht.add(mapId, map1);
        debugger;
        var layer = new esri.layers.ArcGISDynamicMapServiceLayer(url);
        map1.addLayer(layer);

        $("#" + mapId + "_title").html(data);
    }

    function allowDrop(ev) {
        ev.preventDefault();
    }

　　核心部分为：map的销毁函数使用