区分PC端还是移动端

    var os = function() {
        var ua = navigator.userAgent,
        isWindowsPhone = /(?:Windows Phone)/.test(ua),
        isSymbian = /(?:SymbianOS)/.test(ua) || isWindowsPhone, 
        isAndroid = /(?:Android)/.test(ua), 
         isFireFox = /(?:Firefox)/.test(ua), 
         isChrome = /(?:Chrome|CriOS)/.test(ua),
         isTablet = /(?:iPad|PlayBook)/.test(ua) || (isAndroid && !/(?:Mobile)/.test(ua)) || (isFireFox && /(?:Tablet)/.test(ua)),
         isPhone = /(?:iPhone)/.test(ua) && !isTablet,
         isPc = !isPhone && !isAndroid && !isSymbian;
         return {
            isTablet: isTablet,
            isPhone: isPhone,
            isAndroid : isAndroid,
            isPc : isPc
        };
        }();
        if(os.isAndroid || os.isPhone || os.isTablet){
            document.write('mobile')
        }else{
            document.write('pc');
        }