only-one.js

class ThereCanBeOnlyOne {
  timeout = null;

  performAction(waitMs, action) {
    if (this.timeout) this.cancelPrevious();
    return new Promise((resolve, reject) => {
      this.timeout = setTimeout(() => {
        this.cancelPrevious();
        const value = action();
        if (value.then && value.catch) {
          this.handlePromise(value, resolve, reject);
        } else {
          resolve(value);
        }
      }, waitMs);
    });
  }

  handlePromise(promise, resolve, reject) {
    promise
      .then((res) => {
        resolve(res);
      })
      .catch((err) => {
        reject(err);
      });
  }

  cancelPrevious() {
    if (this.timeout) {
      clearTimeout(this.timeout);
      this.timeout = null;
    }
  }
}

export default ThereCanBeOnlyOne;