HTML5 唤起 APP

<p><a href="xxx://app/question/95">点击跳转，直接回帖报名</a></p>

 /* global navigator, document, window */

 var UA = {
     App: navigator.userAgent.indexOf('naitangApp') >= 0,
     WeiXin: navigator.userAgent.indexOf('MicroMessenger') >= 0,
     Android: navigator.userAgent.indexOf('Android') >= 0,
     iPhone: navigator.userAgent.indexOf('iPhone') >= 0
 }
 var timeout
 function replaceSchema(href) {
     var schema = [
         ['xxx://app/question/', 'http://www.xxx.com/question/']
     ]
     var len = schema.length
     for (var i = 0; i < len; i += 1) {
         href = href.replace(schema[i][0], schema[i][1])
     }
     return href
 }
 document.querySelector('body').addEventListener('click', function(e) {
     var tg = (window.event) ? e.srcElement : e.target
     while (tg.nodeName.toUpperCase() !== 'BODY') {
         if (tg && tg.nodeName.toUpperCase() === 'A') {
             var href = tg.getAttribute('href')
             if (href.indexOf('naitang://') === 0) {
                 e.preventDefault()
                 if (UA.App) {
                     window.location.href = href
                 } else if (UA.WeiXin) {
                     window.location.href = 'http://a.app.qq.com/o/simple.jsp?pkgname=com.xxxxxx'
                 } else if (UA.Android) {
                     window.location.href = href
                     timeout = setTimeout(function() {
                         window.location.href = 'http://a.app.qq.com/o/simple.jsp?pkgname=com.xxxxxx'
                     }, 1000)
                 } else if (UA.iPhone) {
                     window.location.href = href
                     timeout = setTimeout(function() {
                         window.location.href = 'itms-apps://itunes.apple.com/cn/app/nai-tang/id00000000?mt=8'
                     }, 1000)
                 } else {
                     var pchref = tg.getAttribute('data-pc')
                     href = pchref ? pchref : replaceSchema(href)
                     window.location.href = href
                 }
             }
             break
         } else {
             tg = tg.parentNode
         }
     }
 }, false)
 function onVisibilityChanged() {
     var hidden = document.hidden || document.webkitHidden
     if (hidden && timeout) {
         window.clearTimeout(timeout)
     }
 }
 document.addEventListener('visibilitychange', onVisibilityChanged, false)