Get the width and height of the screen in real time (adaptive)

The code is almost like this , You can monitor the height and width of the screen at this time , If it changes, then Modify the length and width of the target box  

export default {
    name: 'page-index',
    data(){
        return{
            windowWidth: document.documentElement.clientWidth,  // Real time screen width 
            windowHeight: document.documentElement.clientHeight,   // Real time screen height 
        }
    },    
    methods: {
    },
    // <!-- stay watch Medium monitor real-time width and height -->
    watch: {
      windowHeight (val) {
        let that = this;
        console.log(" Real time screen height ：",val, that.windowHeight );
      },
      windowWidth (val) {
        let that = this;
        console.log(" Real time screen width ：",val, that.windowHeight );
      }
    },

    mounted() {
        var that = this;
        // <!-- hold window.onresize The event hangs to mounted On the function -->
        window.onresize = () => {
            return (() => {
              window.fullHeight = document.documentElement.clientHeight;
                window.fullWidth = document.documentElement.clientWidth;
              that.windowHeight = window.fullHeight;  //  high 
              that.windowWidth = window.fullWidth; //  wide 
            })()
          };
    },
}