Javascript Class to detect browser versions by it's user agent.

gistfile1.js

var Browser = {
    getAgent: function()
    {
        return navigator.userAgent.toLowerCase();
    },

    isMac: function(userAgent)
    {
        var agent = userAgent || this.getAgent();
        return !!agent.match(/mac/i);
    },

    isWin: function(userAgent)
    {
        var agent = userAgent || this.getAgent();
        return !!agent.match(/win/i);
    },

    isWebKit: function(userAgent)
    {
        if(this._isWebKit === undefined)
        {
            var agent = userAgent || this.getAgent();
            this._isWebKit =  !!agent.match(/AppleWebKit/i);
            this.isWebKit = function()
            {
                return this._isWebKit;
            };
        }
        return this._isWebKit;
    },

    isSafari2: function(userAgent)
    {
        if(this._isSafari2 === undefined)
        {
            if (!this.isWebKit())
            {
                this._isSafari2 = false;
            } else {
                var ua = navigator.userAgent.toLowerCase();
               var version = parseInt(parseFloat(ua.substring(ua.lastIndexOf('safari/') + 7)), 10);
                this._isSafari2 = (version >= 419);
            }
            this.isSafari2 = function()
            {
                return this._isSafari2;
            };
        }
        return this._isSafari2;
    },

  isChrome: function(userAgent)
	{
		if(this._isChrome === undefined)
        {
			var agent = userAgent || this.getAgent();
			this._isChrome = !!agent.match(/Chrome/i);
			this.isChrome = function()
            {
				return this._isChrome;
			};
		}
		return this._isChrome;
	},

    isOpera: function(userAgent)
    {
        var agent = userAgent || this.getAgent();
        return !!agent.match(/opera/i);
    },

    isIE: function(userAgent)
    {
        var agent = userAgent || this.getAgent();
        return !!agent.match(/msie/i);
    },

    isIEStrict: function(userAgent)
    {
        var agent = userAgent || this.getAgent();
        return agent.match(/msie/i) && !this.isOpera(agent);
    },

	isIE8: function(userAgent)
    {
		var agent = userAgent || this.getAgent();
		
		var ie = agent.match(/msie\D*([\.\d]*)/i);
		var version = 0;
     	if (ie && ie[1])
        {
        	version = ie[1];
      	}
		
		return version >= 8;
	},
	
    isFirefox: function(userAgent)
    {
        var agent = userAgent || this.getAgent();
        return !!agent.match(/firefox/i);
    },
    
    isiPhone: function(userAgent)
    {
        var agent = userAgent || this.getAgent();
        return !!(this.isWebKit(agent) && agent.match(/iphone/i));
    },

    isiPad: function(userAgent)
    {
        var agent = userAgent || this.getAgent();
        return !!(this.isWebKit(agent) && agent.match(/ipad/i));
    },

    isMobile: function(userAgent)
    {
        var agent = userAgent || this.getAgent();
        return this.isWebKit(agent) && (agent.match(/mobile/i));
    }
};