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I came across offline events with javascript today and depending whats possible i might start playing with it. I maintain a timecard app (website) for a construction company, and a lot of times our field workers are working underground or at locations where a cell signal is impossible. We have been planning to one day migrate this over to a native app eventually, specifically to resolve this one scenario because a native app for sure provides the ability to do background app refreshes.

Im looking for what are the limitations of offline access, When my construction guys do their timecards they currently must have internet, If i re-write some of the features to work offline, I was curious if I can do what native apps can do and defer actions until they are back online?

As far as i'm currently aware there is nothing I can hook into for background syncing when the user has navigated away , but I also know apps like facebook and instagram can send push notifications to my computer from my browser when im not on the webpage, so maybe there is a way?

My main need is for a construction worker to be able to do his timecard, hit submit and put his device away, then for the POST request to succeed when his internet returns, regardless of whether or not his device is open and on my website.