Jassif Team Institution

// Create a new Promise
const myPromise = new Promise((resolve, reject) => {
  // Simulate an async operation (e.g., API call, file read)
  setTimeout(() => {
    const success = Math.random() > 0.5;
    
    if (success) {
      resolve('Operation completed successfully');
    } else {
      reject(new Error('Operation failed'));
    }
  }, 1000); // Simulate delay
});

// Using the Promise
myPromise
  .then(result => console.log('Success:', result))
  .catch(error => console.error('Error:', error.message));

const fs = require('fs').promises;
const promise1 = Promise.resolve('First result');
const promise2 = new Promise((resolve) => setTimeout(() => resolve('Second result'), 1000));
const promise3 = fs.readFile('myfile.txt', 'utf8');

Promise.all([promise1, promise2, promise3])
  .then(results => {
    console.log('Results:', results);
    // results[0] is from promise1
    // results[1] is from promise2
    // results[2] is the content of myfile.txt
  })
  .catch(error => {
    console.error('Error in one of the promises:', error);
  });

function getUser(userId) {
  return new Promise((resolve, reject) => {
    // Simulating database call
    setTimeout(() => {
      resolve({ id: userId, name: 'John' });
    }, 1000);
  });
}

function getUserPosts(user) {
  return new Promise((resolve, reject) => {
    // Simulating API call
    setTimeout(() => {
      resolve(['Post 1', 'Post 2', 'Post 3']);
    }, 1000);
  });
}

// Chain the promises
getUser(123)
  .then(user => {
    console.log('User:', user);
    return getUserPosts(user);
  })
  .then(posts => {
    console.log('Posts:', posts);
  })
  .catch(error => {
    console.error('Error:', error);
  });

const fs = require('fs').promises;
const promise1 = Promise.resolve('First result');
const promise2 = new Promise((resolve) => setTimeout(() => resolve('Second result'), 1000));
const promise3 = fs.readFile('data.txt', 'utf8');

Promise.all([promise1, promise2, promise3])
  .then(results => {
    console.log('Results:', results);
    // results[0] is from promise1
    // results[1] is from promise2
    // results[2] is the content of data.txt
  })
  .catch(error => {
    console.error('Error in one of the promises:', error);
  });

const promise1 = new Promise(resolve => setTimeout(() => resolve('First result'), 1000));
const promise2 = new Promise(resolve => setTimeout(() => resolve('Second result'), 500));

Promise.race([promise1, promise2])
  .then(result => {
    console.log('Fastest result:', result);
    // Will log 'Second result' because promise2 is faster
  });

function fetchData() {
  return new Promise((resolve, reject) => {
    // Simulating an error
    reject(new Error('Network error'));
  });
}

fetchData()
  .then(
    data => console.log('Data:', data),
    error => console.log('Error handled in then:', error.message)
  );

// Alternative method using catch
fetchData()
  .then(data => console.log('Data:', data))
  .catch(error => console.log('Error handled in catch:', error.message));