js 实时获取屏幕高度并赋值

　　 var that = this;
    var h = 1344,w=750;
    var orderHight1 = document.body.clientHeight;
    var orderWidth1 = document.body.clientWidth;
    that.orderHight = orderWidth1*(h/w);
    window.onresize = function(){
    　　orderWidth1 = document.body.clientWidth;
    　　var orderHight2 = orderWidth1*(h/w);
    　　that.orderHight = orderHight2;
  　}