deferred (simple Promise implementation)

deferred.js

// https://gist.github.com/fernandezpablo85/d020ea0efada7f5d4ab746f803ce723c

class deferred {
  thens = []

  then (fn) {
    this.thens.push(fn)
    return this
  }

  done (value) {
    this.thens.reduce(
      (v, fn) => v.then ? v.then(fn) : fn(v),
      value
    )
  }
}