Js判定移动端是否安装app,若已安装，则打开，未安装则跳转到下载页面

判定的js代码如下：

<script type="text/javascript">
    document.getElementById('openApp').onclick = function(e){
        
        if(navigator.userAgent.match(/(iPhone|iPod|iPad);?/i))
           {
            window.location.href = "com.baidu.tieba://";//ios app协议(如：com.baidu.tieba://)
            window.setTimeout(function() {
                window.location.href = "https://itunes.apple.com/cn/app/id477927812"; //跳转到App store
            }, 2000)
           }
        if(navigator.userAgent.match(/android/i))
        {
            window.location.href = "com.baidu.tieba://app";//android app协议(如：com.baidu.tieba://app)
            window.setTimeout(function() {
                window.location.href = "https://****.apk";//android 下载地址
            }, 2000)    
        }
    };
</script>