Hackforge Academy

Explanation

A Promise in JavaScript is an object that
represents the eventual completion or
failure of an
asynchronous operation.

Code:

let promise = new Promise((resolve, reject) => {
  resolve("Success");
});

console.log(promise);

Explanation

A Promise has three states: Pending (initial state),
Fulfilled (operation successful), and Rejected (operation failed).

Code:

#white-// Pending -> Initial state
#white-// Fulfilled -> resolve() called
#white-// Rejected -> reject() called

Explanation

The then() method is used to handle the
result when a Promise is fulfilled.

Code:

let promise = new Promise((resolve) => {
  resolve("Data received");
});

promise.then(result => console.log(result));

Explanation

The catch() method is used to handle errors
when a Promise is rejected.

Code:

let promise = new Promise((resolve, reject) => {
  reject("Error occurred");
});

promise.catch(error => console.log(error));

Explanation

Promises are commonly used for

asynchronous tasks like
API calls or delayed operations.

Code:

function fetchData() {
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve("Data loaded");
    }, 2000);
  });
}

fetchData().then(data => console.log(data));

Explanation

Promises can be chained using multiple then() methods
to perform sequential asynchronous operations.

Code:

Promise.resolve(5)
  .then(num => num * 2)
  .then(result => console.log(result));