检测浏览器的特性

 checkDetect = function(){
            var Detect = {
                webkit: /(AppleWebKit)[ \/]([\w.]+)/,
                ipad: /(ipad).+\sos\s([\d+\_]+)/i,
                windows: /(windows\d*)\snt\s([\d+\.]+)/i,
                iphone: /(iphone)\sos\s([\d+\_]+)/i,
                ipod: /(ipod).+\sos\s([\d+\_]+)/i,
                android: /(android)\s([\d+\.]+)/i
            };

            var ua = window.navigator.userAgent,
                browser = Detect.webkit.exec(ua),
                ios = /\((iPhone|iPad|iPod)/i.test(ua),
                //["iPhone OS 5_1", "iPhone", "5_1"]
                tmp = [],
                N = {},
                match = [];
                for(i in Detect){
                    match = Detect[i].exec(ua);
                    if(match){
                        tmp = Detect[i].exec(ua);
                    }  
                }
                N = {
                    system : tmp[1].toLowerCase(),
                    version : tmp[2].replace(/(\_|\.)/ig, ‘.‘).toLowerCase(),
                    browser : browser ? browser[1].toLowerCase() : ‘apple/webkit‘,
                    ios: ios
                }
                return N;