How to hnadle promise in javacript code example

Example: javascript create promise

// base case
const promise = new Promise(executor);

// more complex example
const coinflip = (bet) => new Promise((resolve, reject) => {
  const hasWon = Math.random() > 0.5 ? true : false;
  if (hasWon) {
    setTimeout(() => {
      resolve(bet * 2);
    }, 2000);
  } else {
    reject(new Error("You lost...")); // same as -> throw new Error ("You lost ...");
  }
});