ArcGIS API for Javascript热区图

有个项目需要用热区图，经研究发现，热区图渲染HeatmapRenderer在ArcGIS js API出现在3.11以后的版本（Added at v3.11），需求是要在自定义的图层里，临时绘制的，不是实际的图层，实现热区图效果，既然不是实际的图层，那也只能在GraphicsLayer存放要素类，但是，HeatmapRenderer仅支持FeatureLayer类型的图层，使用GraphicsLayer没有效果，最后，想到的解决办法是，创建了一个空的FeatureLayer图层，每当需要显示的时候，读取数据，将graphic一个个添加到该图层里即可。其实，FeatureLayer就是GraphicsLayer的一个扩展类。

代码

EsriMethods.addFHeatMapLayer=function() {
    
    //=====================================
    var layerDefinition = {
            "geometryType": "esriGeometryPoint",
            "fields": [{
              "name": "ID",
              "type": "esriFieldTypeInteger",
              "alias": "ID"
            }]
          };
    
          var featureCollection = {
            layerDefinition: layerDefinition,
            featureSet:null
    };
    
    var hFeatureLayer = new EsriDojo.FeatureLayer(featureCollection,{
        mode: EsriDojo.FeatureLayer.MODE_SNAPSHOT,
        opacity:1});
    //hFeatureLayer.graphics=EsriMap.heatMapLayer.graphics;
    EsriMap.map.addLayer(hFeatureLayer);
    
    var heatmapRenderer = new EsriDojo.HeatmapRenderer({
         // field: "ID",
          blurRadius: 10,
          maxPixelIntensity: 30,
          minPixelIntensity: 0
        });
    //var heatmapRenderer = new EsriDojo.HeatmapRenderer();    
    heatmapRenderer.setColorStops([
                                   
                                   { ratio: 0, color: "rgb(255, 219, 0, 0)"},
                                   { ratio: 0.6, color: "rgb(250, 146, 0)"},
                                   { ratio: 0.85, color: "rgb(250, 73, 0)" },
                                   { ratio: 0.95, color: "rgba(250, 0, 0)" }
                                   
                                   
                                   ]);
    
    hFeatureLayer.setRenderer(heatmapRenderer);    
    return hFeatureLayer;
    }

更新：

if(EsriMap.heatMapLayer)
        EsriMap.heatMapLayer.clear();//清除
    else{
        EsriMap.heatMapLayer=EsriMethods.addFHeatMapLayer();
    }

var data = {
            sDate : $('#sDateInput').val(),
            eDate : $('#eDateInput').val(),
            district: district
        };
        $.ajax({
            type : 'POST',
            url : 'rest/system/case/AllCaseByDateToMap/',
            data : JSON3.stringify(data),
            success : function(result) {
                if (result.code == "SUCCESS") {
                    var jsonStr = result.data;
                    var jsonObj = eval(jsonStr);
                    //转json
                    //====================
                    for(var i=0;i