Opening custom protocol URL doesn't work consistently in Chrome - google-chrome

Question

The following code supposes to open a URL in an external app:
var a = document.createElement('a');
a.href = 'myprotocol:jdoe#example.com;fromuser=John%20Doe;mode=audiovideo';
document.body.appendChild(a);
a.click();
When the app is not installed, on some PCs Chrome fails silently while on the others it displays this window:
Where is this behavior defined?

Answer 1

Application association to URI Schema
If you want to register your app to handle a specific URI Schema in Windows, then you should register it in registry. It is explained in MSDN article and Googling "Registering an Application to a URI Scheme" gives plenty of examples.
HKEY_CLASSES_ROOT/
your-protocol-name/
(Default) "URL:your-protocol-name Protocol"
URL Protocol ""
shell/
open/
command/
(Default) PathToExecutable
Web App schema registration
You can register a custom protocol handler with Google Chrome using navigator.registerProtocolHandler (Firefox has the feature too).
navigator.registerProtocolHandler(
'web+mystuff', 'http://example.com/rph?q=%s', 'My App');
Please note, that your protocol has to start with web+. Otherwise you would get SECURITY_ERR: DOM Exception 18 error.
Or, if you are developing a Chrome App, then you can register your handlers in your manifest file.
"url_handlers": {
"view_foo_presentation": {
"matches": [
"https://www.foo.com/presentation/view/*"
],
"title": "View Foo presentation"
}
}
You can also look into the Chrome URLs (chrome://chrome-urls/) and see if you can change it in any of the settings.