schahriar

const getUser = async (query) => {
  const user = await Users.findOne(query);
  const feed = await Feeds.findOne({ user: user._id });
  
  return { user, feed };
};

// getUser will return a promise
getUser({ username: 'test' }).then(...);

schahriar

const fs = require('fs');
const { promisify } = require('util');

// Function#bind as needed
const readFile = promisify(fs.readFile);
const writeFile = promisify(fs.writeFile);

const transform = () => /* ... */;

const transformFileAsync = async (source, dest) => {

schahriar

const throwsLater = async () => {
  await PromiseThatThrows('Some error');
};

async () => {
  try {
    // Note that without await
    // the error will never be
    // caught
    await throwsLater;

schahriar

const PromiseThatThrows = (message) => new Promise((resolve, reject) => {
  // Reject after 100ms with a new error
  setTimeout(() => reject(new Error(message))), 100);
};

schahriar

async (items) => {
  for (let i = 0; i < items.length; i++) {
    const result = await db.get(items[i]);
    console.log(result);
  }
}

schahriar

async (items) => {
  let promises = [];
  
  for (let i = 0; i < items.length; i++) {
    promises.push(db.get(items[i]));
  }
  
  const results = await Promise.all(promises);
  console.log(results);
}

schahriar

async (items) => {
  // Note that async functions return a promise
  const promises = items.map(async (item) => {
    const result = await db.get(item);
    // Log individual results as they finish
    console.log(result);
    return result;
  });
  const results = await Promise.all(promises);
  console.log(results);

schahriar

const [user1, user2] = await Promise.all([db.get('user1'), db.get('user2')]); 

schahriar

const immediatePromise = () => new Promise((resolve) => setImmediate(resolve));
const timeoutPromise = (timeout) => new Promise((resolve) => setTimeout(resolve, timeout));

schahriar

const z = async () => {
  await x();
  await timeoutPromise(1000); // Wait 1 second
  
  // You can recurse z if needed
  return y();
}