测试代码
http://jsbin.com/dipijeqi/11
效果：
chrome
window.devicePixelRatio : 2 (准确)
screen.deviceXDPI / screen.logicalXDPI : NaN
window.outerWidth / window.innerWidth : 2
document.documentElement.offsetHeight / window.innerHeight : 0.020618556701030927 (有相关性)
window.top.outerWidth / window.top.innerWidth : 2
ff
window.devicePixelRatio : 1.5 (准确)
screen.deviceXDPI / screen.logicalXDPI : NaN
window.outerWidth / window.innerWidth : 1.0114583333333333
document.documentElement.offsetHeight / window.innerHeight : 0.023391812865497075 (有相关性)
window.top.outerWidth / window.top.innerWidth : 1.0114583333333333
ie 8
window.devicePixelRatio : undefined
screen.deviceXDPI / screen.logicalXDPI : 1.5416666666666667 (大致准确)
window.outerWidth / window.innerWidth : NaN
document.documentElement.offsetHeight / window.innerHeight : NaN
window.top.outerWidth / window.top.innerWidth : NaN
ie11
window.devicePixelRatio : 1.5 (准确)
screen.deviceXDPI / screen.logicalXDPI : 1.5
window.outerWidth / window.innerWidth : 1.0084033613445377
document.documentElement.offsetHeight / window.innerHeight : 0.02203856749311295 (有相关性)
window.top.outerWidth / window.top.innerWidth : 1.0084033613445377
ie10
window.devicePixelRatio : undefined
screen.deviceXDPI / screen.logicalXDPI : 1.5 (准确)
window.outerWidth / window.innerWidth : 1.0084033613445377
document.documentElement.offsetHeight / window.innerHeight : 1
window.top.outerWidth / window.top.innerWidth : 1.0084033613445377
ie9
window.devicePixelRatio : undefined
screen.deviceXDPI / screen.logicalXDPI : 1.5 (准确)
window.outerWidth / window.innerWidth : 1.0084033613445377
document.documentElement.offsetHeight / window.innerHeight : 1
window.top.outerWidth / window.top.innerWidth : 1.0084033613445377
360 6.3(完全没反应)
window.devicePixelRatio : undefined
screen.deviceXDPI / screen.logicalXDPI : 1
window.outerWidth / window.innerWidth : NaN
document.documentElement.offsetHeight / window.innerHeight : NaN
window.top.outerWidth / window.top.innerWidth : NaN
360极速浏览器
window.devicePixelRatio : 1
screen.deviceXDPI / screen.logicalXDPI : NaN
window.outerWidth / window.innerWidth : 1.5
document.documentElement.offsetHeight / window.innerHeight : 0.015267175572519083
window.top.outerWidth / window.top.innerWidth : 1.5(准确)
搜狗高速浏览器 (完全没反应)
window.devicePixelRatio : undefined
screen.deviceXDPI / screen.logicalXDPI : 1
window.outerWidth / window.innerWidth : NaN
document.documentElement.offsetHeight / window.innerHeight : NaN
window.top.outerWidth / window.top.innerWidth : NaN
淘宝浏览器
window.devicePixelRatio : 1
screen.deviceXDPI / screen.logicalXDPI : NaN
window.outerWidth / window.innerWidth : 2.0710059171597632 (大致准确)
document.documentElement.offsetHeight / window.innerHeight : 0.022988505747126436
window.top.outerWidth / window.top.innerWidth : 2.0710059171597632
