after_idle
after_idle(timeout: Expr, val: Expr)
After idle sets a timer when val updates, when the timer expires it
updates with the value produced by val. If val updates again
before the timer expires, then the timer is reset. The timer is a
number of seconds, fractional seconds are accepted, as well as
durations.
store("/foo", after_idle(0.8, event()))
E.G, do the store only after the user has stopped typing for 800ms.