To Firefox's credit, generally you don't need to. Almost everything I work with, outside of bleeding-edge experimental features, ends up in a setup where I wri

To Firefox's credit, generally you don't need to. Almost everything I work with, outside of bleeding-edge experimental features, ends up in a setup where I write something for chrome and it works flawlessly in Firefox. And safari. It's only IE where solidly "old, tried and true" browser features end up breaking down in bizarre and interesting ways. The only reason we have this big conversation about "supporting" different browsers is because one single holdout has been that bad for so long. And to even MS's credit, I think a large part of that has been the fact that they're not "evergreen" (i.e forcing all users to be on the current version). They've always been doomed by the fact that "what they're judged on" isn't their current work, but is usually the version that's _almost a decade_ out of date.