JS获取活动区域高和宽

var width;
var height;
//获取窗口宽度
if (window.innerWidth)
width = window.innerWidth;
else if ((document.body) && (document.body.clientWidth))
width = document.body.clientWidth;
//获取窗口高度
if (window.innerHeight)
height = window.innerHeight;
else if ((document.body) && (document.body.clientHeight))
height = document.body.clientHeight;