Why do you need a promise

Promises are used to handle asynchronous operations, especially in languages like JavaScript, which often work with non-blocking operations such as network requests, file I/O, and timers. When an operation is asynchronous, it doesn't immediately return a result; instead, it works in the background and provides the result later. Handling this in a clean, organized way can be difficult without a structured approach.

Promises are used to:

1. Handle asynchronous operations.
2. Provide a cleaner alternative to callbacks.
3. Avoid callback hell.
4. Make code more readable and maintainable.

Practical Code Example

// Before Promises: Callback Hell / Pyramid of Doom
getUser(id, (user) => {
  getOrders(user.id, (orders) => {
    getOrderDetails(orders[0].id, (details) => {
      console.log(details);
    });
  });
});

// With Promises: Linear, composable, clean error handling
getUser(id)
  .then((user) => getOrders(user.id))
  .then((orders) => getOrderDetails(orders[0].id))
  .then((details) => console.log(details))
  .catch((err) => console.error('Caught error anywhere in chain:', err));