js 获取页面宽高

var pageWidth = window.innerWidth,
    pageHeight = window.innerHeight;
if (typeof pageWidth != “number”){
    if (document.compatMode == “CSS1Compat”){
        pageWidth = document.documentElement.clientWidth;
        pageHeight = document.documentElement.clientHeight;
    } else {
        pageWidth = document.body.clientWidth;
        pageHeight = document.body.clientHeight;
    }
}