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Node Js · Question Set
Advanced Node Concepts interview questions for placements and exams.
Questions
15
Included in this set
Subject
Node Js
Explore more sets
Difficulty
Mixed
Level of this set
Go through each question and its explanation. Use this set as a focused practice pack for Node Js.
module.exports allows functions, objects, or values to be shared between files. It’s used with require() to import exported members into other modules.
// math.js
module.exports.add=(a,b)=>a+b;
// app.js
const { add }=require('./math');
console.log(add(2,3));For complete preparation, combine this set with full subject-wise practice for Node Js. You can also explore other subjects and sets from the links below.
Tools like ESLint and Prettier enforce consistent formatting and code quality. They integrate with editors and CI pipelines to prevent syntax errors and maintain readable codebases.
NODE_ENV is an environment variable that defines the runtime mode of your app, such as 'development', 'production', or 'test'. It helps configure logging, caching, and debugging behaviors accordingly.
if(process.env.NODE_ENV==='production'){console.log('Running in production');}Node.js provides global timing functions like `setTimeout`, `setInterval`, `setImmediate`, and `process.nextTick`. These schedule functions at different stages of the event loop for asynchronous control.
setTimeout(()=>console.log('Timeout'),1000);
setImmediate(()=>console.log('Immediate'));
process.nextTick(()=>console.log('Next Tick'));WASI (WebAssembly System Interface) allows WebAssembly modules to run in non-browser environments like Node.js. It provides sandboxed access to files and environment variables for better security and performance.
Node.js uses npm or yarn for package management. You can install third-party modules, manage dependencies via package.json, and use scripts for automation. `npm install` reads dependencies and installs them automatically.
npm install express npm list --depth=0
Node.js is fast, scalable, and event-driven. It handles many concurrent connections using non-blocking I/O, making it ideal for real-time applications. Its single-threaded model with the V8 engine ensures efficiency.
The `fork()` method in the child_process module creates a new Node.js process that runs a separate script. It’s useful for scaling CPU-bound tasks or running isolated background jobs.
const { fork } = require('child_process');
const worker = fork('worker.js');
worker.on('message', msg => console.log('Message:', msg));The async.queue() function takes a worker function (that processes tasks) and an optional concurrency limit. It allows you to process multiple tasks in parallel while controlling concurrency.
Synchronous functions block further code execution until completion. Asynchronous functions run in the background and use callbacks, promises, or async/await, allowing Node.js to handle many operations efficiently.
// Sync
const fs=require('fs');
fs.readFileSync('file.txt');
// Async
fs.readFile('file.txt',()=>console.log('Done'));Node.js uses non-blocking asynchronous I/O and an event-driven architecture. Instead of waiting for tasks like file reads or database calls, it delegates them to the event loop and continues executing other code.
Separating your app from the server simplifies testing, scaling, and deployment. The app handles routes and middleware, while the server handles network configuration and listening. This structure improves maintainability.
First-class functions are functions that can be stored in variables, passed as arguments, or returned from other functions. Node.js uses this concept extensively for callbacks and asynchronous handling.
function greet(){return 'Hello';}
function run(fn){console.log(fn());}
run(greet);You mark a function as async and use await to pause execution until a promise resolves. This makes asynchronous code look synchronous, improving readability and error handling.
async function loadData(){
try{
const res=await fetch('https://api.com');
const data=await res.json();
console.log(data);
}catch(err){console.error(err);}
}To connect MongoDB with Node.js, use the official MongoDB driver or Mongoose. You create a client using MongoClient, provide the connection URL, and call `connect()`. Mongoose adds schema and validation features.
const { MongoClient } = require('mongodb');
const uri = 'mongodb://localhost:27017';
const client = new MongoClient(uri);
await client.connect();
console.log('Connected to MongoDB');