安卓/ios判斷是否有某個app如果有就打開 如果沒有就跳轉到下載界面

<script type="text/javascript">
document.getElementById('openApp').onclick = function(e) {
    //ios
    if(navigator.userAgent.match(/(iPhone|iPod|iPad);?/i)) {

        var browser = navigator.userAgent.toLowerCase();

        if(browser.match(/micromessenger/i)) {
            //微信內置瀏覽器
            window.location.href ="PigTrading://";
            window.setTimeout(function() {
                window.location.href = "https://itunes.apple.com/cn/app/zhu-yi-tong/id904595949?l=en&amp;mt=8"; 
            }, 1000)
            return
        } else {
            window.location.href ="PigTrading://";    //ios app協議
            window.setTimeout(function() {
                window.location.href = "https://itunes.apple.com/cn/app/zhu-yi-tong/id904595949?l=en&amp;mt=8";
            }, 2000)
            return
        }
    }

    if(navigator.userAgent.match(/android/i)) {
        //Android
        window.location.href = "zyt://zhuetong/wzydetail?aid=$aid";//安卓協議
        window.setTimeout(function() {
            window.location.href = "http://a.app.qq.com/o/simple.jsp?pkgname=com.lty.zhuyitong"
        }, 2000)
        return
    }

};