ReadonlybackGoes back, as the system back does: closes this screen and answers the screen below it, typed as the screens that can open this one.
ReadonlychangeTaps Done: saves the new username (username). Answers the saved profile.
ReadonlycheckpointTakes a checkpoint of the process with this screen on top: what a fresh
process needs to continue from it (restoreCheckpoint), the stack below
included, without opening any screen again.
ReadonlydataWhat the screen shows: its data, as its data schema types it.
ReadonlyidWhich screen this is: its id in the screen catalog (an item's: its item id).
ReadonlykindWhat kind of thing the screen is: a screen, a tab, an inner tab, a feed or an item.
ReadonlyoriginThe handle this one was opened from: the screen (or the item of its list)
whose call opened it, typed as what can open this screen; undefined for a
launch's or a tab's root.
ReadonlypipePasses the handle through the functions you give, left to right: handle.pipe(f, g) is g(f(handle)).
ReadonlyrawThe answers this visit received from the server, before any decoding; empty on a handle a checkpoint rebuilt.
ReadonlytoThe handle as JSON: its data.
ReadonlytypeTypes a username (username) and checks whether it is available. Answers the screen shown
again; its data.check.available says whether the name is free.
The handle of EditProfileUsernameScreen: what you hold while the screen is open — its
dataand its actions (EditProfileUsernameActions).