js判断浏览浏览器及版本

        var userAgent = navigator.userAgent, 
        rMsie = /(msie\s|trident.*rv:)([\w.]+)/, 
        rFirefox = /(firefox)\/([\w.]+)/, 
        rOpera = /(opera).+version\/([\w.]+)/, 
        rChrome = /(chrome)\/([\w.]+)/, 
        rSafari = /version\/([\w.]+).*(safari)/;
        var browser;
        var version;
        var ua = userAgent.toLowerCase();
        function uaMatch(ua) {
            var match = rMsie.exec(ua);
            if (match != null) {
                return { browser : "IE", version : match[2] || "0" };
            }
            var match = rFirefox.exec(ua);
            if (match != null) {
                return { browser : match[1] || "", version : match[2] || "0" };
            }
            var match = rOpera.exec(ua);
            if (match != null) {
                return { browser : match[1] || "", version : match[2] || "0" };
            }
            var match = rChrome.exec(ua);
            if (match != null) {
                return { browser : match[1] || "", version : match[2] || "0" };
            }
            var match = rSafari.exec(ua);
            if (match != null) {
                return { browser : match[2] || "", version : match[1] || "0" };
            }
            if (match != null) {
                return { browser : "", version : "0" };
            }
        }
        var browserMatch = uaMatch(userAgent.toLowerCase());
        if (browserMatch.browser) {
            browser = browserMatch.browser;
            version = browserMatch.version;
        }
        alert("当前浏览器为："+browser+"；版本为："+version);
        var reg_pwd = /^(?![0-9]+$)(?![a-zA-Z]+$)[0-9A-Za-z]{6,16}$/;