百度社招：实现一个Observable

[Sunny-117]

满足：

const observable = new Observable((sub)=>{
    sub.next(1)
    sub.next(2)
    sub.next(3)
    sub.complete()
})
console.log(observable)

observable.subscribe({
    next: (value)=>console.log('next value', value),
    error: (error)=>console.error(error),
    complete: ()=>console.log('complete')
})

[Windseek]

class Observable {
  constructor(fn) {
    setTimeout(() => {
      fn(this)
    });
  }
  subscribe(args) {
    const { next, error, complete } = args;
    this.next = next;
    this.error = error;
    this.complete = complete;
  }
}

const observable = new Observable((sub)=>{
  sub.next(1)
  sub.next(2)
  sub.next(3)
  sub.complete()
})
console.log(observable)

observable.subscribe({
  next: (value)=>console.log('next value', value),
  error: (error)=>console.error(error),
  complete: ()=>console.log('complete')
})

[Ha0ran2001]

class Observable {
  constructor(fn) {
    this.subscribeFn = fn
  }

  subscribe(observer) {
    const subscriber = {
      next: value => {
        if (observer.next) {
          observer.next(value)
        }
      },
      error: value => {
        if (observer.error) {
          observer.error(value)
        }
      },
      complete: () => {
        if (observer.complete) {
          observer.complete()
        }
      },
    }

    try {
      this.subscribeFn(subscriber)
    } catch (err) {
      subscriber.error(err)
    }

    return {
      unsubscribe: () => {
        subscriber.next = null
        subscriber.error = null
        subscriber.complete = null
      },
    }
  }
}