data(){
    return{
      windowWidth: document.documentElement.clientWidth,  //实时屏幕宽度
      windowHeight: document.documentElement.clientHeight,   //实时屏幕高度
    }
  },
  // <!--在watch中监听实时宽高-->
  watch: {

    windowHeight (val) {

      let that = this;
      console.log("实时屏幕高度：",val, that.windowHeight );
    },
    windowWidth (val) {
      let that = this;
      console.log("实时屏幕宽度：",val, that.windowHeight );
    }
  },
  mounted() {
    var that = this;
    // <!--把window.onresize事件挂在到mounted函数上-->
    window.onresize = () => {
      return (() => {
        window.fullHeight = document.documentElement.clientHeight;
        window.fullWidth = document.documentElement.clientWidth;
        that.windowHeight = window.fullHeight;  // 高
        that.windowWidth = window.fullWidth; // 宽
      })()
    }
  }