» We recommend that web developers avoid UA sniffing as much as possible; modern web platform features are nearly all detectable in easy ways. Over the past year, we’ve seen some UA-sniffing sites that have been updated to detect Microsoft Edge… only to provide it with a legacy IE11 code path. This is not the best approach, as Microsoft Edge matches ‘WebKit’ behaviors, not IE11 behaviors (any Edge-WebKit differences are bugs that we’re interested in fixing). In our experience Microsoft Edge runs best on the ‘WebKit’ code paths in these sites. Also, with the internet becoming available on a wider variety of devices, please assume unknown browsers are good – please don’t limit your site to working only on a small set of current known browsers. If you do this, your site will almost certainly break in the future.

https://blogs.windows.com/msedgedev/2015/06/17/building-a-mo...

Being a large company, I wouldn't expect every team there to have read that. Looks like the Skype Web didn't.

More likely someone said "We don't want to put effort into testing Firefox right now."

> More likely someone said "We don't want to put effort into testing Firefox right now."

The product teams should NOT have to test on Mozilla Firefox. We (disclaimer: I am not an Mozilla employee. Just someone who loves the web.) have a very robust Web Compat program https://github.com/webcompat/web-bugs/issues/27435

and Web Compat is very interested in helping product teams.

I think what the Edge team was trying to say above was detect feature support, not browser vendor. In fact, I would say there are many professionals at Microsoft willing to help the Skype team use feature detection properly. or there is always the Mozilla Developer Documentation https://developer.mozilla.org/en-US/docs/Learn/Tools_and_tes...

Now that’s funny.

This smacks of the bad old days of the web, where UA checking was de rigour (usually to lock sites to IE).

And then, as now, the page usually functioned fine under alternatives with a masked UA.

"Warning: You browser is unsupported. You may experience issues. Continue?" is the only defensible roadblock.

This is why we have alpha's or beta's, such that you can "opt in" but be warned it may break. Simply not supporting a browser at launch is not a good look for your product.

Especially when it's a major product and you literally have thousands of engineers.

They can easily just display a warning that the site is not officially supported on X browser, and the user may run into unexpected errors. This is an active thing that Microsoft is doing, not something they're forced to do.

> In Microsoft's defence, just because its functional, doesn't mean they're ready to spend time supporting it on other clients from day 1.

It’s on the public web. It should work in all major browsers.

EOT

It does work for the majority (> 50%) of users. Is it enough ? No. Is it sufficient to be published ? Yes.