Web 前端 - 浅谈外部手动控制 Promise 状态

前言

　　当有多个共享资源、协同操作的时候，往往需要根据动态亦或是复杂的条件以控制和调用程序逻辑。

设计

1. PendingPromise<T>: type Promise<T> & { resolve:(res?:T)=>void, reject:(e: Error):void }
2. pendingResolve<T>: ()=>PendingPromise<T>

 

实现

 

export type PendingPromise<T> = Promise<T> & { resolve: (T?: any) => void; reject: (e: Error) => void };
export const pendingResolve = <T>() => {
  const container = {} as any;
  container.p = new Promise((r, j) => ([container.r, container.j] = [r, j]));
  [container.p.resolve, container.p.reject] = [container.r, container.j];
  return container.p as PendingPromise<T>;
};

 

使用

 

const pending = pendingResolve<Date>();
(async () => console.log(await pending) )();
pending.resolve(new Date("2020-01-01"));


// Wed Jan 01 2020 08:00:00 GMT+0800 (中国标准时间)