Keep references of timeouts and promises to help during graceful shutdown

keep-refs.js

// Pending promises
let execs = []
// Timeouts waiting to run
let timeouts = []

const exec = (func, ...args) => {
  const promise = func(...args).finally(() => {
    // Cleanup after the promise settled (resolved or rejected)
    execs = execs.filter((el) => el !== promise)
  })
  // Add the promise to the array so it may be cleaned up later
  execs = [ ...execs, promise ]
  return promise
}

const delayExec = (func, ms, ...args) => {
  const timeout = setTimeout((callback, argsArr) => {
    // Cleanup after the delay has completed
    timeouts = timeouts.filter((el) => el !== timeout)
    // Finally execute the function
    exec(callback, ...argsArr)
  }, ms, func, args)
  // Add the timeout to the array so it may be cleaned up later
  timeouts = [ ...timeouts, timeout ]
  return timeout
}