abort-controller-dance.js

class Signal extends EventTarget {
  #aborted = false;
  constructor(controller) {
    super();
    // one of those cases where unreachable listener
    // is actually desired 'cause it's more secure
    this.addEventListener('abort', event => {
      if (event.detail !== controller)
        event.stopImmediatePropagation();
      else
        this.#aborted = true;
    });
  }
  get aborted() {
    return this.#aborted;
  }
}

class Controller {
  constructor() {
    this.signal = new Signal(this);
  }
  abort() {
    this.signal.dispatchEvent(new CustomEvent('abort', {detail: this}));
  }
}

const contr = new Controller;
const {signal} = contr;
signal.addEventListener('abort', console.log);

signal.dispatchEvent(new Event('abort')); // nope
console.log(signal.aborted);  // false

// only the signal owner can make it abort 👍
contr.abort();  // yup
console.log(signal.aborted);  // true