javascript之IE版本检测

function getIEVersion()
{
        var rv = -1; // Return value assumes failure.
        if(navigator.appName == ‘Microsoft Internet Explorer‘) {
                var ua = navigator.userAgent;
                var re = new RegExp("MSIE ([0-9]{1,}[\.0-9]{0,})");
if(re.exec(ua) != null)
        rv = parseFloat(RegExp.$1);
}
return rv;
}

function checkVersion() {
        var msg = "You‘re not using Internet Explorer.";
        var ver = getIEVersion();

        if(ver > -1) {
                alert(ver);
                if(ver >= 9.0)//这里写明要检测的版本
                        msg = "You‘re using a recent copy of Internet Explorer."
                else
                        msg = "You should upgrade your copy of Internet Explorer.";
        }
        alert(msg);
}