Detecting re-open of an Android Chrome HTML Webapp

Question

Recent versions of Chrome on Android have added the ability to create full screen Webapps using the 'mobile-web-app-capable' meta tag in much the same way that you can on iOS.

On iOS when you quit a web app and open it again it will always be refreshed; on Chrome it will be up to the operating system resources; and if you re-open the same web app it will often restore the previous app context without reloading the page.

This is causing problems for my Weather Web App as on re-open it often displays old forecast data which can be days out of date.

Is there a way to detect the page re-open so that I can refresh/reload the content?

Answer 1

It seems that the trick is to use timers. Usually, when a webapp is in the background (not a tab background) it's frozen, so it's not executing code. Therefore, if you have a javascript timer that executes every X seconds and on one execution you see that the time passed between executions is far greater then it means that you need to update your data.