The page visibility api does not function properly with homescreen apps on the iPhone/iPad on iOS 11. To repro: 1. In Safari on an iPhone or iPad with iOS 11, go to https://andrewjdr.github.io/pagevis-api-safari-standalone-broken/ 2. Add this to your homescreen. 3. Open the newly created homescreen app. 4. Start playing the video. 5. Press the sleep button on the iPhone/iPad. 6. Unexpectedly, the visibilitychange event handler is never called, and the audio continues to play. Furthermore, document.hidden is always "false", even when the screen is locked (verified via setInterval in web inspector). Compare this to the expected result, which you can observe by performing the same steps within safari proper (without going through the homescreen app): 1. In Safari on an iPhone or iPad with iOS 11, go to https://andrewjdr.github.io/pagevis-api-safari-standalone-broken/ 2. Start playing the video. 3. Press the sleep button on the iPhone/iPad. 4. As expected, visibilitychange handler is called, and the audio stops playing. document.hidden is correctly set to "true" when the screen is locked. I believe this is a major issue, because homescreen apps that are computation heavy (and thus battery-consuming) have no way of detecting that the device has been locked so that they can stop their expensive computations or work. Additionally, onblur/onfocus events also do not fire. As far as I know, there is no way of detecting that the page is no longer visible from a homescreen app when the screen becomes locked.