Node.js Async/Await

What is Async/Await?

• async: Declares an asynchronous function and implicitly returns a Promise.
• await: Pauses the execution inside an async function until a Promise resolves or rejects.

Async/await allows developers to write asynchronous code in a synchronous-looking style, improving readability and maintainability.

Benefits of Async/Await

• Improved Readability
• Simplified Error Handling using try...catch
• Avoids Callback Nesting
• Synchronous-Like Flow

Example 1: Simulating Asynchronous Operation

Output:

Example 2: Handling File System Asynchronously

Output:

Example 3: Using try...catch for Error Handling

Output:

Example 4: Running Promises in Parallel

Output:

Important Rules of Async/Await

• Await must be inside an async function
• Async functions always return Promises, even when returning simple values
• Await only pauses inside async functions, not globally
• Use try...catch for error handling inside async functions

Practical Use Cases in Node.js

• Reading and writing files using fs.promises
• Making HTTP requests using axios or http
• Asynchronous database queries
• Introducing delays with setTimeout inside Promises

When Not to Use Await

Avoid using await inside forEach. Use:

• for...of loops with await for sequencing
• Promise.all() for parallel execution

Key Takeaways

• Async/await simplifies handling of asynchronous operations in Node.js
• Improves code readability over callbacks and .then()
• Error handling is cleaner with try...catch
• Essential for modern Node.js development workflows