获取浏览器类型和版本

var userAgent = navigator.userAgent.toLowerCase();
    var 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 )
    };