1177296 - Wrong performance.marks placements?

Status: RESOLVED WONTFIX

(Firefox OS Graveyard :: Gaia::Settings, defect)

Description

[Zibi Braniecki [:zbraniecki][:gandalf]]

Settings is the only app we have that has contentInteractive fired before navigationLoaded[0].

According to the spec[1] contentInteractive should happen when content is visible (so after visuallyLoaded) and visuallyLoaded should happen after navigation is both loaded and interactive. 


[0] http://raptor.mozilla.org/#/dashboard/script/apps.js?device=flame-kk&branch=master&memory=319&series=coldlaunch.*&panelId=11&fullscreen
[1] https://developer.mozilla.org/en-US/Apps/Build/Performance/Firefox_OS_app_responsiveness_guidelines

Comment 1

[Zibi Braniecki [:zbraniecki][:gandalf]]

Eli, can you confirm that?

Comment 2

[:Eli Perelman]

So thinking about this, I think Gandalf is correct about how the markers should work, but I can't say I know enough about the Settings app startup flow to know if the events are in the correct place or not. Regardless, I think you've raised a good point about the definition of contentInteractive. With the current definition...

> Emit this marker when your application designates that it has bound the events for the minimum set of functionality to allow the user to interact with the "above-the-fold" content made available at visuallyLoaded.

...it is entirely possible for contentInteractive to fire before visuallyLoaded as we don't make the distinction in the definition itself that the user actually *can* interact with these elements. For example:

```
<section hidden class="above-the-fold"></section>

var section = document.querySelector('section');

section.addEventListener('click', () => navigate());
performance.mark('contentInteractive');

section.removeAttribute('hidden');
performance.mark('visuallyLoaded');
```

I don't think this should be allowed. We should modify the definition to make it clear that contentInteractive should not be fired until the user has the ability to interact with the elements made available in visuallyLoaded. That would then make the above example code into this:

```
var section = document.querySelector('section');

section.addEventListener('click', () => navigate());
section.removeAttribute('hidden');

performance.mark('contentInteractive');
performance.mark('visuallyLoaded');
```

I'd venture to say though that you can still fire contentInteractive before visuallyLoaded as the order isn't dependent, but there should not be a gap between them if that is the case. Probably easier to understand if visuallyLoaded is fired first. :)

Comment 3

[BMO Automation]

Firefox OS is not being worked on