NODE.JS · EASY CODEX

Node.js Interview Questions — Easy

Q: What is Node.js and what is its primary use case?

Definition: Node.js is an open-source, cross-platform JavaScript runtime environment built on Google Chrome's V8 engine. Primary Use Case: Building fast, scalable network applications, real-time commu

Q: How does Node.js handle concurrency if it runs on a single thread?

Single Thread: JavaScript code executes on a single main thread (the call stack). Asynchronous Delegation: When an asynchronous, blocking operation (e.g., file system access, network requests, databas

Q: What is the V8 engine and how does Node.js leverage it?

Definition: V8 is Google's high-performance, open-source JavaScript engine written in C++. JIT Compilation: V8 compiles JavaScript directly to native machine code before executing it, bypassing interm

Q: What is Libuv and why is it crucial to Node.js?

Definition: Libuv is a multi-platform support library written in C, specifically designed for Node.js to handle asynchronous I/O. Core Responsibilities: Implements the Event Loop. Manages the internal

Q: What is the Event Loop in Node.js?

Purpose: The event loop is the mechanism that allows Node.js to perform non-blocking I/O operations despite being single-threaded. Mechanism: It continuously polls the operating system and task queues

Core concepts, definitions, basic syntax, and first principles expected in round 1 screening.

50 Theory Questions7 Implementation Folios5 Free Model Answers

THEORY QUESTIONS & SOLUTIONSShowing 5 of 50 questions

Q1What is Node.js and what is its primary use case?

Definition: Node.js is an open-source, cross-platform JavaScript runtime environment built on Google Chrome's V8 engine.
Primary Use Case: Building fast, scalable network applications, real-time communication tools (WebSockets, chat), REST APIs, and microservices.
Architecture: Uses a single-threaded, event-driven, and non-blocking I/O model to achieve high concurrency without the overhead of thread context-switching.

Q2How does Node.js handle concurrency if it runs on a single thread?

Single Thread: JavaScript code executes on a single main thread (the call stack).
Asynchronous Delegation: When an asynchronous, blocking operation (e.g., file system access, network requests, database queries) is encountered, Node.js delegates it to the OS kernel or the Libuv thread pool.
Callbacks/Events: Once the delegated operation completes, the result is queued as a callback in the Event Loop, which executes it when the call stack becomes empty.

Q3What is the V8 engine and how does Node.js leverage it?

Definition: V8 is Google's high-performance, open-source JavaScript engine written in C++.
JIT Compilation: V8 compiles JavaScript directly to native machine code before executing it, bypassing intermediate bytecode interpretation.
Role in Node: V8 manages memory allocation, provides call stack execution, and performs garbage collection. Node.js adds binding APIs (C++ bindings) to allow JavaScript to interact with OS-level components like files and networks.

Q4What is Libuv and why is it crucial to Node.js?

Definition: Libuv is a multi-platform support library written in C, specifically designed for Node.js to handle asynchronous I/O.
Core Responsibilities:
- Implements the Event Loop.
- Manages the internal Thread Pool (usually 4 threads by default) for blocking tasks.
- Abstracts OS-specific asynchronous mechanisms like epoll (Linux), kqueue (macOS), and IOCP (Windows).

Q5What is the Event Loop in Node.js?

Purpose: The event loop is the mechanism that allows Node.js to perform non-blocking I/O operations despite being single-threaded.
Mechanism: It continuously polls the operating system and task queues, pushing completed asynchronous callbacks onto the call stack for execution.
Loop Cycle: If there are no active connections, timers, or pending operations, the event loop terminates.

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