Can't you just make everything display:none until you're ready to show it? -Jeff
On Thu, Jul 30, 2015 at 4:20 PM, James Burke <jbu...@mozilla.com> wrote: > There are some forces at play in a web app that point to wanting to delay > layout and rendering until a web app gives a signal that it should start: > > * ECMAScript modules, and even developer constructed JS module systems > today, rely on async loading of scripts. > > * Custom elements need their JS registered with the browser before they are > fully useful. > > * Apps can have dependencies on async IDB operations to know what UI to > first show. For instance, if the user does not have a saved account, show > the sign in view instead of the app data view. > > * We want fast app startups in B2G/Gaia. Typically we lose > layout/render/paint time while we wait for these async mechanisms to > finish, and the paints are not useful for the user in the meantime. > > In addition, there is a possibility that custom elements may take a path of > synchronous construction with no later upgrades, which means the JS for the > custom element needs to be registered before any custom element is used in > the DOM. > > A similar case surfaced a while back in the context of B2G, and at the time > I filed bug 863499[2], which focused on a document.mozDelayLoadEvent / > document.mozStopDelayingLoadEvent JS API around controlling the load event > firing. > > At that time, the concern was about losing times to wasted renders and the > effects on screen shots. > > However, I believe the main concern now is getting enough JS and app data > loaded to allow layout to be effective in fewer passes than strictly about > the final render and load event. So maybe the API should be more about > delaying layout than about the load event? > > In talking to Wilson Page, he mentioned something like a > document.pauseLayout() document.resumeLayout(), not sure if there are > existing thoughts around that. > > If that seemed workable, maybe also a <html mozPauseLayout> type of > attribute, so the browser knows as soon as possible to pause its work, > instead of relying on a JS API. > > For Gaia apps, we use a CSP policy that does not allow inline scripts, so > the attribute on a tag is more appealing for that reason. A nonced script > might be a workable alternative for the CSP case, if an attribute was too > much of a stretch. > > Happy to hear about any suggestions for the general goal, > James > > [1] Service workers help a bit here, but do not help the other aync forces. > [2] https://bugzilla.mozilla.org/show_bug.cgi?id=863499 > _______________________________________________ > dev-platform mailing list > dev-platform@lists.mozilla.org > https://lists.mozilla.org/listinfo/dev-platform _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
