跨浏览器获取可视浏览器的长度

var width = window.innerWidth;var height = window.innerHeight;if (typeof width != 'number') {    if (typeof document.compatMode == 'CSS1Compat') {        width = document.documentElement.clientWidth;        height = document.documentElement.clientHeight;    }else{        width = document.body.clientWidth;        height = document.body.clientHeight;    }};