All I could find was this, from the article: "It’ll be a while before all browsers support background sync, especially as Safari and Edge don’t yet support service workers."

It talks about using code to check to see if it's supported in the user's browser under "Progressive Enhancement".

It's got a spec https://wicg.github.io/BackgroundSync/spec/, and Mozilla is interested https://groups.google.com/a/chromium.org/forum/m/#!topic/bli...