ArcGIS.js实现地图超出底图范围自动回弹

this.gisMap.on('extent-change',this.showExtent)

// An highlighted block
let fullExtent={
    xmin: xx,
    ymin: xx,
    xmax: xx,
    ymax: xx,
   }
showExtent(extS){
   let ext=extS.extent;  
    if(ext.xmin<this.fullExtent.xmin||ext.xmax>this.fullExtent.xmax||ext.ymax>this.fullExtent.ymax||ext.ymin<this.fullExtent.ymin){
    let fullExtent = new esri.geometry.Extent(
     {
      ...this.fullExtent, 
      spatialReference:new esri.SpatialReference({ wkid: parseInt(4490) })//SpatialReference设置地图坐标系
     }
    );
    this.gisMap.setExtent(fullExtent);
   }
  },