async-reducer-context/src/sub.ts

通过react-context,useReducer替代redux，可扩展支持与redux周边middleware中间件，通过useModel(['key'])可获取state和dispatch，其中useModel已做到获取的属性值变化，组件才会重新渲染，摆脱useContext因context中无关数据导致的重复渲染问题。

class Subs {
  observers: Function[]

  constructor() {
    this.observers = [];
  }

  add(observer: Function) {
    this.observers.push(observer);
  }

  notify() {
    this.observers.forEach((observer) => observer());
  }

  delete(observer: Function) {
    const index = this.observers.findIndex((item) => item === observer);
    if (index > -1) {
      this.observers.splice(index, 1);
    }
  }
}

export default Subs;