很常见的功能，鼠标点击获取点击的经纬度。

var handler = new Cesium.ScreenSpaceEventHandler(viewer.scene.canvas); //此方法获取鼠标点击位置经纬度
    handler.setInputAction(function (e) {
      var position = viewer.scene.pickPosition(e.position);
      //将笛卡尔坐标转化为经纬度坐标
      var cartographic = Cesium.Cartographic.fromCartesian(position);
      var longitude = Cesium.Math.toDegrees(cartographic.longitude);
      var latitude = Cesium.Math.toDegrees(cartographic.latitude);
      var height = cartographic.height;
      console.log(longitude,latitude,height)
      viewer.camera.setView({//定位到范围中心点
        destination: Cesium.Cartesian3.fromDegrees(Number(longitude), Number(latitude), 2000),
        orientation: {
          heading: Cesium.Math.toRadians(180),//1
          pitch: Cesium.Math.toRadians(-90),
          roll: 0
        }
      });
      }, Cesium.ScreenSpaceEventType.LEFT_CLICK);