Subscription manager to quickly remove all subs (on componentWillUnmount for eg.)

subscriptionManager.js

export default createSubscriptionManager = () => {
  const subs = []

  return {
    subscriptions: subs,
    interval: attachSubscriptionMethod(subs, interval),
    listen: attachSubscriptionMethod(subs, listen),
    timeout: attachSubscriptionMethod(subs, timeout),
    promise: attachSubscriptionMethod(subs, promise),
  
    remove: function() {
      subs.forEach(sub => sub.remove())
      subs.splice(0, subs.length)
      return this
    }
  }
}

const attachSubscriptionMethod = (subs, callback) => (...args) => {
  const sub = callback(...args)
  subs.push(sub)
  return sub
}


// Subscription methods

const timeout = (...args) => {
  const ref = setTimeout(...args);
  return {
    remove: () => clearTimeout(ref)
  }
}

const interval = (...args) => {
  const ref = setInterval(...args);
  return {
    remove: () => clearInterval(ref)
  }
}

const promise = promise => {
  let removed, resolve, reject
  promise.then(
    res => !removed && resolve(res),
    err => !removed && reject(err),
  )
  return Object.assign(new Promise((res, rej) => {
      resolve = res
      reject = rej
    }),
    { remove: () => removed = true }
  )
}

const listen = (listener, ...args) => listener.addEventListener(...args)