AI solution for JavaScript Coding Question on BFE.dev
71. implement Observable Subject

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

  subscribe(observer) {
    this.observers.push(observer);
  }

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

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

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

Explanation:

1. We define a class called Subject.
2. In the constructor, we initialize an empty array called observers to hold all the observers subscribed to the subject.
3. We define a method subscribe to add an observer to the observers array.
4. We define a method next to dispatch the next value to all the observers in the observers array.
5. We define a method error to dispatch an error to all the observers in the observers array.
6. We define a method complete to signal the completion of the observable to all the observers in the observers array.