Node.js FAQ: Top Questions

A callback function is a function passed as an argument to another function, executed after an asynchronous operation completes, often following the error-first pattern.

• Error-First: Callback receives error as the first parameter, then data.
• Issues: Can lead to "callback hell" (nested callbacks).
• Alternatives: Promises or async/await for cleaner code.
• Use Case: Handling async operations like file I/O, HTTP requests.