js 弹出div层随游览器大小始终居中

//获取通用的高度s

function findDimensions() {
    if (window.innerWidth) winWidth = window.innerWidth;
    else
        if ((document.body) && (document.body.clientWidth))
        winWidth = document.body.clientWidth;

    if (window.innerHeight) winHeight = window.innerHeight;
    else if ((document.body) && (document.body.clientHeight)) winHeight = document.body.clientHeight;

    if (document.documentElement && document.documentElement.clientHeight && document.documentElement.clientWidth)
    { winHeight = document.documentElement.clientHeight; winWidth = document.documentElement.clientWidth; }

    return winHeight;

//return winWidth;s

}