Launch app if installed or redirect to download - windows

Stack Overflown asked in this question:

On every repo, GitHub has a button that is labelled "Clone in Desktop" (example: http://ift.tt/JrUfBN). If you have GitHub for Mac installed, the href is something like "github-mac://openRepo/http://ift.tt/JrUfBN". This opens GitHub for Mac and offers to clone the repo. If you don't, the href is "http://mac.github.io". This is a download page for GitHub for Mac. I would like to do something similar on my website: open my app if installed and redirect to download if not. How can this be best accomplished?

The answer was about Github Conduit, but, as far as I know, Github Conduit is only for Github for Mac.



I have the same question, only for Windows operating systems. How does GitHub know whether GitHub is installed on a computer, or not?

---

As deepcurious said in their answer, we need to use the following code that checks if a protocol is registered:

$("a[href*='github-windows://']").click(function(e) {
    var el = $(this);
    setTimeout(function() {
        window.location = el.data("data-href-alt");
    }, 200);

    // once you do the custom-uri, it should properly execute the handler, otherwise, the settimeout that you set before will kick in
    window.location = el.data("href");

    e.preventDefault();
});

and I have the following HTML link:

<a href="github-windows://openRepo/https://github.com/jquery/api.jqueryui.com" data-href-alt="http://ift.tt/1DmqS01">Clone in Desktop</a>

If the app is installed, Google Chrome gives me an External Protocol Request (below), so I assume it should work (although it does nothing on my computer). But, if the app is not installed, it does not go to the data-href-alt page.

For example, if I change github-windows:// to some-uninstalled-app:// in all instances in the code, the link does nothing.