在onLoad()里面已经将windowWidth保存到data中,在滚动事件的代码中写代码，war width=this.data.windowWidth,却报错提示，类型{}上不存在属性”windowWidth“.如果在滚动事件代码中把onLoad中的代码：var systemInfo = systemInfo.windowWidth var windowWidth = systemInfo.widowWidth;var width = windowWidth,写进去，就不会报这样的错，这是生命原因？如果多个地方需要用到这个属性，那不是每次都得重新写一遍？

onLoad() {
    var systemInfo=wx.getSystemInfoSync();
    var windowHeight = systemInfo.windowHeight;
    var windowWidth = systemInfo.windowWidth;
    var width = windowWidth;
    var height = 100; 
    var radius = (height/2)+(width*width/8/height);
    var left = -(radius-width/2);
    this.setData({
      windowHeight:windowHeight,
      windowWidth:windowWidth,
      radius:radius,
      left:left
    })
  },
/**
   * 滚动的事件
   */
  scrollEvent:function(event:any){
    var scrollTop = event.detail.scrollTop;
    if(scrollTop > 0 && scrollTop <= 100){
      var height = 100-scrollTop;
      var width = this.data.windowWidth;
      // var systemInfo=wx.getSystemInfoSync();
      // var windowWidth = systemInfo.windowWidth;
      // var width = windowWidth;
      var radius = (height/2)+(width*width/8/height);
      var left = -(radius-width/2);
      this.setData({
        radius:radius,
        left:left
      })
    }
   
  },