Timeout API

API for delays
for animation use rAF instead
runs in (almost) every tick, much more often than screen can refresh
runs in background even if tab is not visible
beware: inefficient ❗️
beware: delay is only the minimum delay, needs to wait until event loop has run all tasks that are already in macrotask queue ❗️

`setTimeout()`

WindowOrWorkerGlobalScope.setTimeout(callback, delay)

executes callback once after a delay in ms
returns unique identifier, integer
if timer has not yet elapsed can cancel using clearTimeout(timeoutID) (or clearInterval(timeoutID) since setInterval() shares the same ID pool)
beware: an invalid ID does not throw an error ❗️
this inside callback will be back to default (global object / undefined in non- / strict mode) since callback is passed as argument to another function, can preserve it by wrapping value of callback in anonymous function❗️

setTimeout(() => {callback()}, delay)

use recursive setTimeout for constant delay between previous call end and next call start
use setInterval for constant delay between consecutive call starts
nested setTimeout calls are throttled by browser, in foreground maximal every 4 ms, in background maximal every 1s

WindowOrWorkerGlobalScope.setInterval(callback, delay)

executes callback repeatedly every delay in ms, simple loop
returns unique identifier, integer
if timer has not yet elapsed can cancel using clearInterval(timeoutID) (or clearTimeout(timeoutID) since setTimeout() shares the same ID pool)
beware: an invalid ID does not throw an error ❗️
this inside callback will be back to default (global object / undefined in non- / strict mode) since callback is passed as argument to another function, can preserve it by wrapping value of callback in anonymous function❗️

setInterval(() => {callback()}, delay)

use setInterval for constant delay between consecutive call starts
use recursive setTimeout for constant delay between previous call end and next call start
beware: interval does not adjust to how long code takes to run, i.e. if code runs longer than delay, next call is run even before previous returned ❗️
setInterval calls are throttled by browser, in foreground maximal every 4 ms, in background maximal every 1s