JQuery 判断浏览器及其版本

function JudgeBroswer() { 
        if($.browser.msie) { 
            alert("this is msie!"); //IE
        } 
        else if($.browser.safari) 
        { 
            alert("this is safari!"); //Safari 
        } 
        else if($.browser.mozilla) 
        { 
            alert("this is mozilla!");  //Firefox
        } 
        else if($.browser.opera) { 
            alert("this is opera");     //Opera
        } 
    }

var userAgent = navigator.userAgent.toLowerCase();
    // Figure out what browser is being used 
    jQuery.browser = {
        version: (userAgent.match(/.+(?:rv|it|ra|ie)[\/: ]([\d.]+)/) || [])[1],
        safari: /webkit/.test(userAgent),
        opera: /opera/.test(userAgent),
        msie: /msie/.test(userAgent) && !/opera/.test(userAgent),
        mozilla: /mozilla/.test(userAgent) && !/(compatible|webkit)/.test(userAgent)
    };

$.browser.msie&&($.browser.version == "6.0")&&!$.support.style 

$.browser.msie&&($.browser.version == "7.0")