<script type='text/javascript' src='//g.alicdn.com/sj/lib/zepto/zepto.min.js' charset='utf-8'></script>

$(function(){
        (function ($) {
    "use strict";
    var device = {};
    var ua = navigator.userAgent;

    var android = ua.match(/(Android);?[\s\/]+([\d.]+)?/);
    var ipad = ua.match(/(iPad).*OS\s([\d_]+)/);
    var ipod = ua.match(/(iPod)(.*OS\s([\d_]+))?/);
    var iphone = !ipad && ua.match(/(iPhone\sOS)\s([\d_]+)/);

    device.ios = device.android = device.iphone = device.ipad = device.androidChrome = false;

    // Android
    if (android) {
        device.os = 'android';
        device.osVersion = android[2];
        device.android = true;
        device.androidChrome = ua.toLowerCase().indexOf('chrome') >= 0;
    }
    if (ipad || iphone || ipod) {
        device.os = 'ios';
        device.ios = true;
    }
    // iOS
    if (iphone && !ipod) {
        device.osVersion = iphone[2].replace(/_/g, '.');
        device.iphone = true;
    }
    if (ipad) {
        device.osVersion = ipad[2].replace(/_/g, '.');
        device.ipad = true;
    }
    if (ipod) {
        device.osVersion = ipod[3] ? ipod[3].replace(/_/g, '.') : null;
        device.iphone = true;
    }
    // iOS 8+ changed UA
    if (device.ios && device.osVersion && ua.indexOf('Version/') >= 0) {
        if (device.osVersion.split('.')[0] === '10') {
            device.osVersion = ua.toLowerCase().split('version/')[1].split(' ')[0];
        }
    }

    // Webview
    device.webView = (iphone || ipad || ipod) && ua.match(/.*AppleWebKit(?!.*Safari)/i);

    // Minimal UI
    if (device.os && device.os === 'ios') {
        var osVersionArr = device.osVersion.split('.');
        device.minimalUi = !device.webView &&
            (ipod || iphone) &&
            (osVersionArr[0] * 1 === 7 ? osVersionArr[1] * 1 >= 1 : osVersionArr[0] * 1 > 7) &&
            $('meta[name="viewport"]').length > 0 && $('meta[name="viewport"]').attr('content').indexOf('minimal-ui') >= 0;
    }

    // Check for status bar and fullscreen app mode
    var windowWidth = $(window).width();
    var windowHeight = $(window).height();
    device.statusBar = false;
    if (device.webView && (windowWidth * windowHeight === screen.width * screen.height)) {
        device.statusBar = true;
    }
    else {
        device.statusBar = false;
    }

    // Classes
    var classNames = [];

    // Pixel Ratio
    device.pixelRatio = window.devicePixelRatio || 1;
    classNames.push('pixel-ratio-' + Math.floor(device.pixelRatio));
    if (device.pixelRatio >= 2) {
        classNames.push('retina');
    }

    // OS classes
    if (device.os) {
        classNames.push(device.os, device.os + '-' + device.osVersion.split('.')[0], device.os + '-' + device.osVersion.replace(/\./g, '-'));
        if (device.os === 'ios') {
            var major = parseInt(device.osVersion.split('.')[0], 10);
            for (var i = major - 1; i >= 6; i--) {
                classNames.push('ios-gt-' + i);
            }
        }

    }
    // Status bar classes
    if (device.statusBar) {
        classNames.push('with-statusbar-overlay');
    }
    else {
        $('html').removeClass('with-statusbar-overlay');
    }

    // Add html classes
    if (classNames.length > 0) $('html').addClass(classNames.join(' '));

    // keng..
    device.isWeixin = /MicroMessenger/i.test(ua);

    $.device = device;
})(Zepto);

console.log($.device)
// --------
{
    android: true
    androidChrome: false
    ios: false
    ipad: false
    iphone: false
    isWeixin: false
    os: "android"
    osVersion: "4.4.1"
    pixelRatio: 3
    statusBar: false
    webView: null
}

// arg1 > arg2, return 1; arg1 == arg2, return 0; arg1 < arg2, return -1
$.compareVersion('8.0', '7.1.1')
// return 1
$.compareVersion('4.2', $.device.osVersion)
// return -1
$.compareVersion('5.0', '5.0')
// return 0