Asynchronous Programming

Node.js is asynchronous by nature, which means it doesn’t wait for I/O operations (like reading a file or a database) to complete before moving to the next task.

1. Promises

A Promise represents the eventual completion (or failure) of an asynchronous operation.

const myPromise = new Promise((resolve, reject) => {
  const success = true;
  if (success) {
    resolve("Operation successful!");
  } else {
    reject("Something went wrong.");
  }
});

myPromise
  .then((data) => console.log(data))
  .catch((err) => console.error(err));

2. Async / Await

Introduced in ES2017, async/await is a cleaner way to write asynchronous code that looks and behaves like synchronous code.

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

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

readFile();

Why it matters

Asynchronous code prevents “blocking” the Event Loop, allowing Node.js to handle thousands of concurrent connections efficiently.

[!IMPORTANT] Always use try/catch blocks when using await to handle errors properly.