js 在web页面中判断某程序是否安装，未安装则下载

近期拿到一个需要，需要在web页面中判断我们的一个程序是否安装，未安装则下载
直接上代码
 //检查是否安装程序 begin
function check(uri, failCb, successCb, unsupportedCb) {
    function failCallback() {
        failCb && failCb();
    }
 
    function successCallback() {
        successCb && successCb();
    }
 
    if (navigator.msLaunchUri) { //for IE and Edge in Win 8 and Win 10
        openUriWithMsLaunchUri(uri, failCb, successCb);
    } else {
        var browser = checkBrowser();
 
        if (browser.isFirefox) {
            openUriUsingFirefox(uri, failCallback, successCallback);
        } else if (browser.isChrome || browser.isIOS) {
            openUriWithTimeoutHack(uri, failCallback, successCallback);
        } else if (browser.isIE) {
            openUriUsingIEInOlderWindows(uri, failCallback, successCallback);
        } else if (browser.isSafari) {
            openUriWithHiddenFrame(uri, failCallback, successCallback);
        } else {
            unsupportedCb();
            //not supported, implement please
        }
    }
}
 
//for IE and Edge in Win 8 and Win 10
function openUriWithMsLaunchUri(uri, failCb, successCb) {
    navigator.msLaunchUri(uri,
        successCb,
        failCb
    );
}
 
//检查浏览器类型
function checkBrowser() {
    var isOpera = !!window.opera || navigator.userAgent.indexOf(' OPR/') >= 0;
    var ua = navigator.userAgent.toLowerCase();
    return {
        isOpera: isOpera,
        isFirefox: typeof InstallTrigger !== 'undefined',
        isSafari: (~ua.indexOf('safari') && !~ua.indexOf('chrome')) || Object.prototype.toString.call(window.HTMLElement).indexOf('Constructor') > 0,
        isIOS: /iPad|iPhone|iPod/.test(navigator.userAgent) && !window.MSStream,
        isChrome: !!window.chrome && !isOpera,
        isIE: /*@cc_on!@*/false || !!document.documentMode // At least IE6
    }
}
 
//Firefox
function openUriUsingFirefox(uri, failCb, successCb) {
    var iframe = document.querySelector("#hiddenIframe");
 
    if (!iframe) {
        iframe = _createHiddenIframe(document.body, "about:blank");
    }
 
    try {
        iframe.contentWindow.location.href = uri;
        successCb();
    } catch (e) {
        if (e.name == "NS_ERROR_UNKNOWN_PROTOCOL") {
            failCb();
        }
    }
}
 
function openUriWithTimeoutHack(uri, failCb, successCb) {
 
    var timeout = setTimeout(function () {
        failCb();
        handler.remove();
    }, 1000);
 
    //handle page running in an iframe (blur must be registered with top level window)
    var target = window;
    while (target != target.parent) {
        target = target.parent;
    }
 
    var handler = _registerEvent(target, "blur", onBlur);
 
    function onBlur() {
        clearTimeout(timeout);
        handler.remove();
        successCb();
    }
 
    window.location = uri;
}
 
function openUriUsingIEInOlderWindows(uri, failCb, successCb) {
    if (getInternetExplorerVersion() === 10) {
        openUriUsingIE10InWindows7(uri, failCb, successCb);
    } else if (getInternetExplorerVersion() === 9 || getInternetExplorerVersion() === 11) {
        openUriWithHiddenFrame(uri, failCb, successCb);
    } else {
        openUriInNewWindowHack(uri, failCb, successCb);
    }
}
 
function openUriWithHiddenFrame(uri, failCb, successCb) {
 
    var timeout = setTimeout(function () {
        failCb();
        handler.remove();
    }, 1000);
 
    var iframe = document.querySelector("#hiddenIframe");
    if (!iframe) {
        iframe = _createHiddenIframe(document.body, "about:blank");
    }
 
    var handler = _registerEvent(window, "blur", onBlur);
 
    function onBlur() {
        clearTimeout(timeout);
        handler.remove();
        successCb();
    }
 
    iframe.contentWindow.location.href = uri;
}
 
function _registerEvent(target, eventType, cb) {
    if (target.addEventListener) {
        target.addEventListener(eventType, cb);
        return {
            remove: function () {
                target.removeEventListener(eventType, cb);
            }
        };
    } else {
        target.attachEvent(eventType, cb);
        return {
            remove: function () {
                target.detachEvent(eventType, cb);
            }
        };
    }
}
 
function _createHiddenIframe(target, uri) {
    var iframe = document.createElement("iframe");
    iframe.src = uri;
    iframe.id = "hiddenIframe";
    iframe.style.display = "none";
    target.appendChild(iframe);
 
    return iframe;
}
 
function getInternetExplorerVersion() {
    var rv = -1;
    if (navigator.appName === "Microsoft Internet Explorer") {
        var ua = navigator.userAgent;
        var re = new RegExp("MSIE ([0-9]{1,}[\.0-9]{0,})");
        if (re.exec(ua) != null)
            rv = parseFloat(RegExp.$1);
    }
    else if (navigator.appName === "Netscape") {
        var ua = navigator.userAgent;
        var re = new RegExp("Trident/.*rv:([0-9]{1,}[\.0-9]{0,})");
        if (re.exec(ua) != null) {
            rv = parseFloat(RegExp.$1);
        }
    }
    return rv;
}
 
function openUriInNewWindowHack(uri, failCb, successCb) {
    var myWindow = window.open('', '', 'width=0,height=0');
 
    myWindow.document.write("<iframe src='" + uri + "'></iframe>");
 
    setTimeout(function () {
        try {
            myWindow.location.href;
            myWindow.setTimeout("window.close()", 1000);
            successCb();
        } catch (e) {
            myWindow.close();
            failCb();
        }
    }, 1000);
}
 
function openUriUsingIE10InWindows7(uri, failCb, successCb) {
    var timeout = setTimeout(failCb, 1000);
    window.addEventListener("blur", function () {
        clearTimeout(timeout);
        successCb();
    });
 
    var iframe = document.querySelector("#hiddenIframe");
    if (!iframe) {
        iframe = _createHiddenIframe(document.body, "about:blank");
    }
    try {
        iframe.contentWindow.location.href = uri;
    } catch (e) {
        failCb();
        clearTimeout(timeout);
    }
}
//检查是否安装程序 end

function openUrl(protocolUrl){
        check(protocolUrl, function () {
                //no install, go download page
                console.log("程序未安装")
                myconfirm();
            },()=>{
              console.log("已安装")
            });
        event.preventDefault ? event.preventDefault() : event.returnValue = false;
    }
function myconfirm(){
  if (confirm("检测到程序未安装，是否需要安装？")) {
  // 用户点击了确认按钮
  // 在这里执行你想要执行的操作
  console.log("确认下载")
  var url='xxx';//下载链接
    window.location.href=url;//下载

  
} else {
  // 用户点击了取消按钮，不需要执行任何操作
    console.log("取消下载")
}
}

openUrl('xxx://'); //这里替换为你需要的自定义协议 比如微信程序就是weixin://
解释一下本段代码：需要看到最后两个函数，前边的不需要改动
openUrl('xxx://'); //这里替换为你需要的自定义协议比如微信程序就是weixin://
var url='xxx';//下载链接
window.location.href=url;//下载
这个url需要自行更改 http https下载链接均可。
具体效果如下
如有其他问题，欢迎在评论区沟通交流。
js 在web页面中判断某程序是否安装，未安装则下载

悦读
