Hey I think you were on the right track. It is definitly not that easy but chrome so far was not my problem, more like Edge + IE but my solution is assuming they don't support the protocol if anything fails or they don't respond correctly which they do sometimes.
The blur/focus is something to check but you need to check it in combination with a visibility change. The HTML5 Visiblity API and this post about it helped me figure out a solution that is pretty solid except the mentioned browsers above because they have some issues with the navigator.msLaunchUri function and have their own approach implemented which doesn't rely on blur/focus. But the function is bugged and doesn't respond correctly all the time.
You can find my codepen here. Hopefully that helps you even though it is a bit late for an answer. This works for mobile browsers as well but I didn't test multiple yet worked for my Android 6.0.2. Might need some tweaks in the long run but I think it is pretty solid.
(function() {
var noProtocolHash = '#protocolXYnotsupported',
checkDelay = 800, // apps might start slowly
isBlurred = false,
inCheck = false,
inLauncherCheck = false,
tabVisible = (function(){
var stateKey,
eventKey,
keys = {
hidden: "visibilitychange",
webkitHidden: "webkitvisibilitychange",
mozHidden: "mozvisibilitychange",
msHidden: "msvisibilitychange"
};
for (stateKey in keys) {
if (stateKey in document) {
eventKey = keys[stateKey];
break;
}
}
return function(c) {
if (c) document.addEventListener(eventKey, c);
return !document[stateKey];
}
})(),
isMSIE = function(){
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.$1);
}
}
return (rv !== -1)? true: false;
},
isEdge = function(){
return window.navigator.userAgent.indexOf("Edge") > -1;
},
checkIfFocusLost = function($el){
try {
document.location.href = $el.attr("href");
} catch (ex) {
document.location.href = document.location.href + '/' + noProtocolHash;
}
setTimeout(checkVisibility, checkDelay);
},
checkVisibility = function(){
if(tabVisible() && !isBlurred){
handleNoProtocol();
}
else {
handleProtocol();
}
},
handleNoProtocol = function(){
$('.result').text('has no protocol');
inLauncherCheck = false;
},
handleProtocol = function(){
$('.result').text('has the protocol');
inLauncherCheck = false;
},
checkHash = function(){
if(document.location.hash === noProtocolHash){
handleNoProtocol();
}
},
checkLauncherProtocol = function($el){
inLauncherCheck = true;
navigator.msLaunchUri($el.attr("href"), function(){
handleProtocol();
},
function(){
handleNoProtocol();
});
setTimeout(function(){
// fallback when edge is not responding correctly
if(inLauncherCheck === true){
handleNoProtocol();
}
}, 500);
},
checkIfHasProtocol = function($el){
inCheck = true;
if(isEdge() || isMSIE()){
checkLauncherProtocol($el);
}
else {
checkIfFocusLost($el)
}
};
checkHash();
tabVisible(function(){
if(tabVisible() && inCheck){
handleProtocol();
inCheck = false;
}
});
window.addEventListener("blur", function(){
isBlurred = true;
});
window.addEventListener("focus", function(){
isBlurred = false;
inCheck = false;
});
window.checkIfHasProtocol = checkIfHasProtocol;
})();
$('.protocol').click(function(e) {
checkIfHasProtocol($(this));
e.preventDefault();
});
My code is tested with Win10: Chrome, Firefox, IE11, Edge + Android: Chrome (6.0.1)
there is also this github project https://github.com/ismailhabib/custom-protocol-detection which sorta has a similar approach maybe a little bit more maintained but i couldn't get their solution working for some reasons but maybe this is exactly what you need.
