A promise whose results can be discarded; a quick and dirty substitute for canceling Fetch API

SilenceablePromise.ts

class SilenceablePromise<T> extends Promise<T> {
  silence: () => void

  constructor(
    executor: (
      resolve: (value?: T | PromiseLike<T>) => void,
      reject: (reason?: any) => void,
    ) => void,
  ) {
    let silence: any
    super((resolve, reject) => {
      let silenced = false
      silence = () => { silenced = true }
      const wrap = (fn: typeof resolve) => (value: any) => { if (!silenced) fn(value) }
      executor(wrap(resolve), wrap(reject))
    })
    this.silence = silence
  }
}

const p = new SilenceablePromise((resolve) => {
  window.setTimeout(resolve, 200)
})
p.then(console.log, console.error)
p.silence()

const silenceableFetch = (input: RequestInfo, init?: RequestInit) =>
  new SilenceablePromise((resolve, reject) => fetch(input, init).then(resolve, reject))