Hackforge Academy

Category: React • Beginner

Published on 18 Feb 2026

Explanation

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

Code Example

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

console.log(promise);

Explanation

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

Code Example

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

Explanation

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

Code Example

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

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

Explanation

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

Code Example

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

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

Explanation

#white-Promises are commonly used for #white-#white-asynchronous tasks like #white-API calls or delayed operations.

Code Example

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

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

Explanation

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

Code Example

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