User agent as a runtime | Blog | Decade City
Ultimately you can’t control when and how things go wrong but you do have some control over what happens. This is why progressive enhancement exists.
Link tags: useragents
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gaia/build/ua-override-prefs.js at master · mozilla-b2g/gaia · GitHub
And this is why user-agent sniffing not a future-friendly technique. A new mobile browser comes along, and it has to spoof a fake UA string to all of these sites.
It’s a Red Queen arms race.