JavaScript Interview Questions

Node.js is a powerful JavaScript runtime that allows you to run JavaScript code outside of a browser, typically on servers. It runs on Google’s V8 engine and follows a non-blocking, event-driven architecture, making it ideal for managing high volumes of simultaneous client requests without slowing down.

Using process.nextTick() Node.js schedules a function to run right after the current operation completes, but before the event loop continues with new tasks.

setImmediate() executes the callback after the current event loop phase is completed.

spawn – Executes a command and returns a stream (useful for large outputs).

exec – It's great for executing commands and collecting their full response, but only if you're expecting a small result.

fork – Used to create a new child process with IPC (Inter-Process Communication).

The event loop handles asynchronous callbacks in Node. It allows Node to perform non-blocking I/O operations.

Non-blocking I/O means the server continues processing requests while I/O operations are happening in the background.

Streams are objects for reading or writing data continuously. Types: Readable, Writable, Duplex, Transform.

Node uses the child_process module to spawn and manage child processes for tasks like running shell commands.

CommonJS uses require(), ES Modules use import/export. Node.js supports both CommonJS and ES Modules, although ES Modules are the more modern standard introduced in recent versions.

It contains project info, dependencies, scripts, and configuration. It’s essential for managing any Node project.

Middleware are functions that execute in the request-response cycle. Useful for auth, logging, body parsing, etc.

Clustering allows Node to spawn multiple worker processes to handle load across CPU cores for better performance.