Jassif Team Institution

async function getData() {
  console.log('Starting...');
  const result = await someAsyncOperation();
  console.log(`Result: ${result}`);
  return result;
}

function someAsyncOperation() {
  return new Promise(resolve => {
    setTimeout(() => resolve('Operation completed'), 1000);
  });
}

// Call the async function
getData().then(data => console.log('Final data:', data));

const fs = require('fs').promises;

async function readFile() {
  try {
    const data = await fs.readFile('myfile.txt', 'utf8');
    console.log(data);
  } catch (error) {
    console.error('Error reading file:', error);
  }
}

readFile();

async function fetchUserData() {
  try {
    const response = await fetch('https://api.example.com/users/1');
    if (!response.ok) {
      throw new Error(`HTTP error: ${response.status}`);
    }
    const user = await response.json();
    console.log('User data:', user);
    return user;
  } catch (error) {
    console.error('Error fetching user data:', error);
    throw error; // Re-throw the error if needed
  }
}

// Helper function to simulate an API call
function fetchData(id) {
  return new Promise(resolve => {
    setTimeout(() => resolve(`Data for ID ${id}`), 1000);
  });
}

// Sequential operation - takes ~3 seconds
async function fetchSequential() {
  console.time('sequential');
  const data1 = await fetchData(1);
  const data2 = await fetchData(2);
  const data3 = await fetchData(3);
  console.timeEnd('sequential');
  return [data1, data2, data3];
}

// Parallel operation - takes ~1 second
async function fetchParallel() {
  console.time('parallel');
  const results = await Promise.all([
    fetchData(1),
    fetchData(2),
    fetchData(3)
  ]);
  console.timeEnd('parallel');
  return results;
}

// Demo
async function runDemo() {
  console.log('Running sequentially...');
  const seqResults = await fetchSequential();
  console.log(seqResults);
  
  console.log('\nRunning in parallel...');
  const parResults = await fetchParallel();
  console.log(parResults);
}

runDemo();

// Using async/await
async function getUserAndPosts() {
  try {
    const user = await getUserPromise(1);
    console.log('User:', user);
    
    const posts = await getUserPostsPromise(user);
    console.log('Posts:', posts);
  } catch (error) {
    console.error(error);
  }
}

getUserAndPosts();

async function myFunction() {
  return 'Hello';
}

// This returns a Promise that resolves to 'Hello', not the string 'Hello' directly
const result = myFunction();
console.log(result); // Promise { 'Hello' }

// You need to await it or use .then()
myFunction().then(message => console.log(message)); // Hello

const util = require('util');
const fs = require('fs');

// Convert callback-based function to Promise-based
const readFile = util.promisify(fs.readFile);

async function readFileContents() {
  const data = await readFile('file.txt', 'utf8');
  return data;
}