@segment/analytics-generic-utils/src/create-deferred/create-deferred.ts

This monorepo's version of "lodash". This package contains shared generic utilities that can be used within the ecosystem. This package should not have dependencies, and should not contain any references to the Analytics domain.

/**
 * Return a promise that can be externally resolved
 */
export const createDeferred = <T>() => {
  let resolve!: (value: T | PromiseLike<T>) => void
  let reject!: (reason: any) => void
  let settled = false
  const promise = new Promise<T>((_resolve, _reject) => {
    resolve = (...args) => {
      settled = true
      _resolve(...args)
    }
    reject = (...args) => {
      settled = true
      _reject(...args)
    }
  })

  return {
    resolve,
    reject,
    promise,
    isSettled: () => settled,
  }
}