Add example usage of onrelease event.

[scheib]

The WakeLockSentinel onrelease event is "used to notify scripts that a given WakeLockSentinel object's handle has been released, either due to the release() method being called or because the wake lock was released by the user agent."

For spec readability it would help to have usage examples.

[rakuco]

Isn't that covered by example 2, which has

navigator.wakeLock.request("screen").then(lock => {
  checkbox.checked = true;

  const listener = (ev) => {
    checkbox.checked = false;
    ev.target.removeEventListener('release', listener);
  };

  lock.addEventListener('release', listener);
});

?

[marcoscaceres]

We should await that and use more spec terms in the example.

[marcoscaceres]

(@rakuco you are correct is what I mean - but could be clearer)

[rakuco]

How about this:

const sentinel = await navigator.wakeLock.request('screen');
checkbox.checked = true;

const listener = (ev) => {
  checkbox.checked = false;
  ev.target.remoteEventListener('release', listener);
};

sentinel.onrelease = listener;

(not sure whether it's clearer to use onrelease or addEventListener for symmetry)

[marcoscaceres]

I like it :) @scheib, wdyt? Would that be clearer? We should also make sure we have a link to the relevant example.

[scheib]

First, I apologize having overlooked that there was an example. I looked adjacent to the release event definition, and searched the page for 'onrelease', and didn't take the time to find example 2.

I do like the rework. Using 'onrelease' will help others who make my mistake. As would having the example linked or moved to be in context.

Also, might keep it even simpler by directly assigning the function and not de-registering it. Focusing just on what's needed to demonstrate the spec:

const sentinel = await navigator.wakeLock.request('screen');
checkbox.checked = true;

sentinel.onrelease = () => checkbox.checked = false;

Are there any other things we expect apps to do when lock is lost? Attempt to reacquire? That's blocked because user activation is needed. Any other possible action other than just notifying the user in UI that lock is lost?

[rakuco]

#251 updates the example and hopefully makes it easier to find and understand.

Are there any other things we expect apps to do when lock is lost? Attempt to reacquire? That's blocked because user activation is needed. Any other possible action other than just notifying the user in UI that lock is lost?

Note that user activation is needed only when a UA sets the permission to "prompt". The Chromium implementation, for example, always grants screen wake locks regardless of whether the request was triggered by user activation or not.