🚀 Web Development Interview Questions with Answers — Part 5: Node.js

🧠 111. What is Node.js?

Node.js is a JavaScript runtime built on Chrome’s V8 engine.

It allows JavaScript to run outside the browser.

Features:

✅ Fast execution

✅ Event-driven

✅ Non-blocking I/O

✅ Scalable applications

Example:

console.log("Hello Node.js");

🧠 112. Why Use Node.js?

Advantages:

✅ Fast performance

✅ Single programming language for frontend & backend

✅ Handles multiple requests efficiently

✅ Huge npm ecosystem

Best Use Cases:

• APIs

• Real-time apps

• Chat applications

• Streaming services

🧠 113. What is npm?

npm stands for: 👉 Node Package Manager

Used to install libraries/packages.

Example:

npm install express

Uses:

• Install packages

• Manage dependencies

• Run scripts

🧠 114. Difference Between CommonJS and ES Modules

CommonJS : Uses require() : Uses module.exports

ES Modules : Uses import : Uses export

CommonJS:

const fs = require("fs");

ES Modules:

import fs from "fs";

🧠 115. What is Express.js?

Express.js is a minimal backend framework for Node.js.

Features:

✅ Routing

✅ Middleware support

✅ API development

Example:

const express = require("express");

const app = express();

app.get("/", (req, res) => {

res.send("Hello");

});

🧠 116. What is Middleware?

Middleware functions execute between: Request → Response

Uses:

• Authentication

• Logging

• Validation

Example:

app.use((req, res, next) => {

console.log("Middleware");

next();

});

🧠 117. What is REST API?

REST API follows REST architecture principles.

Common Methods:

• GET

• POST

• PUT

• DELETE

Example:

app.get("/users", (req, res) => {

res.json(users);

});

🧠 118. Difference Between PUT and PATCH

PUT : Updates entire resource

PATCH : Updates partial resource

Example:

PUT /user/1

PATCH /user/1

🧠 119. What is JWT?

JWT stands for: 👉 JSON Web Token

Used for authentication.

Structure:

Header.Payload.Signature

Benefits:

✅ Secure authentication

✅ Stateless sessions

🧠 120. What is Authentication vs Authorization?

Authentication : Verifies identity

Authorization : Verifies permissions

Example:

• Login → Authentication

• Admin access → Authorization

🧠 121. What is CORS?

CORS stands for: 👉 Cross-Origin Resource Sharing

It controls resource sharing between different domains.

Example:

app.use(cors());

🧠 122. What is dotenv?

dotenv loads environment variables from .env file.

Example:

require("dotenv").config();

.env

PORT=5000

🧠 123. What is Event Loop?

Event loop handles asynchronous operations in Node.js.

Process:

1. Executes synchronous code

2. Handles callbacks

3. Processes async tasks

Benefits:

✅ Non-blocking execution

✅ Efficient concurrency

🧠 124. What is Non-Blocking I/O?

Node.js can process multiple requests without waiting.

Benefits:

✅ Faster performance

✅ Better scalability

🧠 125. What is package.json?

package.json stores project metadata and dependencies.

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Example:

{

"name": "myapp",

"version": "1.0.0"

}

🧠 126. What is nodemon?

nodemon automatically restarts server after code changes.

Install:

npm install -g nodemon

🧠 127. What are Streams in Node.js?

Streams process data piece by piece instead of loading all at once.

Types:

• Readable

• Writable

• Duplex

• Transform

Benefits:

✅ Memory efficient

✅ Faster processing

🧠 128. What is Buffering?

Buffer temporarily stores binary data in memory.

Example:

const buffer = Buffer.from("Hello");

🧠 129. What is Async Middleware?

Middleware using async/await.

Example:

app.get("/", async (req, res) => {

const data = await fetchData();

res.json(data);

});

🧠 130. What is Rate Limiting?

Rate limiting restricts number of requests from users.

Benefits:

✅ Prevents abuse

✅ Protects APIs

✅ Improves security

Example:

const rateLimit = require("express-rate-limit");

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🚀 Web Development Interview Questions with Answers — Part 6: Database

🧠 131. What is SQL?

SQL stands for: 👉 Structured Query Language

It is used to manage and manipulate relational databases.

Uses:

• Store data

• Retrieve data

• Update records

• Delete records

Example:

SELECT * FROM users;

🧠 132. Difference Between SQL and NoSQL

SQL : Relational database : Uses tables : Structured schema

NoSQL : Non-relational database : Uses collections/documents : Flexible schema

Examples:

• SQL → MySQL

• NoSQL → MongoDB

🧠 133. What is Primary Key?

Primary key uniquely identifies each record in a table.

Features:

✅ Unique

✅ Cannot be NULL

Example:

CREATE TABLE users (

id INT PRIMARY KEY,

name VARCHAR(50)

);

🧠 134. What is Foreign Key?

Foreign key creates relationship between two tables.

Example:

CREATE TABLE orders (

order_id INT,

user_id INT,

FOREIGN KEY (user_id) REFERENCES users(id)

);

🧠 135. What is Normalization?

Normalization organizes database to reduce redundancy.

Normal Forms:

• 1NF

• 2NF

• 3NF

Benefits:

✅ Reduced duplication

✅ Better consistency

✅ Improved integrity

🧠 136. What are Joins in SQL?

Joins combine data from multiple tables.

Types:

• INNER JOIN

• LEFT JOIN

• RIGHT JOIN

• FULL JOIN

Example:

SELECT users.name, orders.amount

FROM users

INNER JOIN orders

ON users.id = orders.user_id;

🧠 137. Difference Between INNER JOIN and LEFT JOIN

INNER JOIN : Returns matching rows only

LEFT JOIN : Returns all left table rows

Example:

SELECT * FROM users

LEFT JOIN orders

ON users.id = orders.user_id;

🧠 138. What is Indexing?

Index improves database query performance.

Benefits:

✅ Faster searches

✅ Faster filtering

Example:

CREATE INDEX idx_name

ON users(name);

🧠 139. What is Aggregate Function?

Aggregate functions perform calculations on multiple rows.

Common Functions:

• COUNT()

• SUM()

• AVG()

• MIN()

• MAX()

Example:

SELECT COUNT(*) FROM users;

🧠 140. Difference Between DELETE, DROP, and TRUNCATE

DELETE : Removes rows : Can use WHERE

DROP : Removes table : Deletes structure

TRUNCATE : Removes all rows : Faster than DELETE

Example:

DELETE FROM users WHERE id = 1;

🧠 141. What is MongoDB?

MongoDB is a NoSQL database that stores data in JSON-like documents.

Features:

✅ Flexible schema

✅ High scalability

✅ Fast performance

Example Document:

{

"name": "Deepak",

"age": 25

}

🧠 142. Difference Between MongoDB and MySQL

MongoDB : NoSQL : Flexible schema : Document-based

MySQL : SQL : Fixed schema : Table-based

🧠 143. What is Schema?

Schema defines structure of database.

Example:

CREATE TABLE users (

id INT,

name VARCHAR(50)

);

🧠 144. What is ORM?

ORM stands for: 👉 Object Relational Mapping

ORM allows interaction with database using programming language objects.

Benefits:

✅ Easier queries

✅ Cleaner code

✅ Faster development

🧠 145. What is Sequelize?

Sequelize is an ORM for Node.js.

Example:

User.findAll();

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Benefits:

✅ Easy database interaction

✅ Supports SQL databases

🧠 146. What is Mongoose?

Mongoose is an ODM library for MongoDB.

Example:

const User = mongoose.model("User", userSchema);

🧠 147. What are ACID Properties?

ACID ensures reliable database transactions.

Properties:

• Atomicity

• Consistency

• Isolation

• Durability

Benefits:

✅ Data reliability

✅ Transaction safety

🧠 148. What is Transaction?

Transaction is a group of database operations executed together.

Example:

BEGIN;

UPDATE accounts

SET balance = balance - 500

WHERE id = 1;

COMMIT;

🧠 149. What is Database Sharding?

Sharding splits database into smaller parts.

Benefits:

✅ Better scalability

✅ Faster performance

🧠 150. What is Replication?

Replication copies database data across multiple servers.

Benefits:

✅ High availability

✅ Backup support

✅ Fault tolerance

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⌨️ CSS Flexbox Tutorial for Beginners | Basics & Container | 1/2

Responsive design is more important than ever as we want to ensure that our website looks awesome on all devices. With Flexbox we can make our Elements more dynamic, so let's find out how this works in this tutorial!