cancellable_promise_2.js

function wait(signal, ms) {
  return new Promise((res, rej) => {
    const timeOut = setTimeout(() => {
      console.log("I was called");
      res("ok");
    }, ms);

    signal.catch(err => {
      rej(err);
      clearTimeout(timeOut);
    });
  });
}

function createCancellableSignal() {
  const ret = {};
  ret.signal = new Promise((resolve, reject) => {
    ret.cancel = () => {
      reject(new Error("Promise was cancelled"));
    };
  });

  return ret;
}

const { signal, cancel } = createCancellableSignal();

const promise = wait(signal, 1000);
promise.then(res => console.log(res)).catch(err => console.log(err));

cancel();