Creating promises in Javascript - Try It Yourself

Creating promises

📖 Scenario: You are building a simple app that simulates checking if a user is logged in. This check takes some time, so you will use a promise to handle the waiting.

🎯 Goal: Create a promise that waits 2 seconds and then resolves with the message "User is logged in". Then display this message.

📋 What You'll Learn

Create a promise called loginCheck that waits 2 seconds before resolving

Use setTimeout inside the promise executor function

Resolve the promise with the exact string 'User is logged in'

Use loginCheck.then to get the resolved message

Print the resolved message using console.log

💡 Why This Matters

🌍 Real World

Promises are used in web apps to handle tasks like loading data from servers, waiting for user input, or running animations smoothly.

💼 Career

Understanding promises is essential for frontend and backend JavaScript developers to write clean, readable, and efficient asynchronous code.

1

Create the loginCheck promise

Create a promise called loginCheck using new Promise with an executor function that takes resolve and reject as parameters.

Javascript

// Your code here

Need a hint?

Use new Promise((resolve, reject) => { }) to create the promise.

2

Add a 2-second delay and resolve the promise

Inside the loginCheck promise executor, use setTimeout to wait 2000 milliseconds, then call resolve with the string 'User is logged in'.

Javascript

const loginCheck = new Promise((resolve, reject) => {
  // Your code here
});

Need a hint?

Use setTimeout(() => { resolve('User is logged in'); }, 2000) inside the promise.

3

Use then to get the resolved message

Use loginCheck.then with a function that takes a parameter message and inside it, call console.log(message).

Javascript

const loginCheck = new Promise((resolve, reject) => {
  setTimeout(() => {
    resolve('User is logged in');
  }, 2000);
});

// Your code here

Need a hint?

Use loginCheck.then(message => console.log(message)) to print the message.

4

Print the resolved message

Run the program and observe that after 2 seconds, the console prints User is logged in.

Javascript

const loginCheck = new Promise((resolve, reject) => {
  setTimeout(() => {
    resolve('User is logged in');
  }, 2000);
});

loginCheck.then(message => {
  console.log(message);
});

// Your code here

Need a hint?

Wait 2 seconds after running to see the message printed in the console.