└── README.md /README.md: -------------------------------------------------------------------------------- 1 | # 100 Node Js Important Interview Questions 2 | 3 | ### Node.js Basics: 4 | 5 | 1. What is Node.js? 6 | 2. Explain the architecture of Node.js. 7 | 3. How does Node.js handle concurrent requests? 8 | 4. What is the role of the event loop in Node.js? 9 | 5. Describe the use of the V8 engine in Node.js. 10 | 6. How can you install a package using npm? 11 | 7. Explain the purpose of the `package.json` file. 12 | 8. Differentiate between `process.nextTick()` and `setImmediate()`. 13 | 9. What is the purpose of the `Buffer` class in Node.js? 14 | 10. How can you handle environment variables in Node.js? 15 | 16 | ### Modules and Dependency Management: 17 | 18 | 11. What is a module in Node.js? 19 | 12. How do you create a custom module in Node.js? 20 | 13. Explain the difference between `require` and `import` in Node.js. 21 | 14. Describe the CommonJS module system. 22 | 15. What is the purpose of the `module.exports` object? 23 | 16. How do you handle circular dependencies in Node.js? 24 | 17. Explain the significance of the `node_modules` folder. 25 | 18. What are the differences between `npm install` and `npm ci`? 26 | 19. How can you update dependencies to their latest versions using npm? 27 | 20. What is the purpose of the `package-lock.json` file? 28 | 29 | ### Asynchronous Programming: 30 | 31 | 21. Explain the concept of callback functions in Node.js. 32 | 22. What is the Event Emitter class in Node.js, and how is it used? 33 | 23. Describe the purpose of the `Promise` object in Node.js. 34 | 24. How do you handle errors in asynchronous code in Node.js? 35 | 25. Compare and contrast callbacks and Promises. 36 | 26. What is the purpose of the `async` and `await` keywords in Node.js? 37 | 27. Explain the role of the `setTimeout` function in asynchronous programming. 38 | 28. How does Node.js handle blocking and non-blocking code? 39 | 29. Describe the use of the `process.nextTick()` function. 40 | 41 | ### Web Development with Node.js: 42 | 43 | 30. How can you create a simple HTTP server in Node.js? 44 | 31. Explain the difference between `res.send` and `res.end` in Express.js. 45 | 32. What is middleware in Express.js? 46 | 33. How do you handle form data in an Express.js application? 47 | 34. Explain the purpose of the Express.js Router. 48 | 35. What is the purpose of the `app.use` function in Express.js? 49 | 36. How can you implement routing in an Express.js application? 50 | 37. Describe the role of the `body-parser` middleware. 51 | 38. What is RESTful API, and how can you implement it in Node.js? 52 | 39. How do you handle file uploads in an Express.js application? 53 | 54 | ### Security in Node.js: 55 | 56 | 40. Explain the concept of Cross-Origin Resource Sharing (CORS). 57 | 41. How can you prevent SQL injection in a Node.js application? 58 | 42. What is the purpose of the Helmet middleware in Express.js? 59 | 43. Describe how to handle authentication in Node.js. 60 | 44. How can you protect against common security vulnerabilities in Node.js? 61 | 45. Explain the significance of the Same-Origin Policy. 62 | 46. How do you implement HTTPS in a Node.js application? 63 | 47. Describe the purpose of the `crypto` module in Node.js. 64 | 65 | ### Testing in Node.js: 66 | 67 | 48. What is unit testing, and how can you perform it in Node.js? 68 | 49. Explain the purpose of the `assert` module in Node.js. 69 | 50. How do you use Mocha for testing in Node.js? 70 | 51. What is Chai, and how is it used in testing? 71 | 52. Describe the difference between unit testing and integration testing. 72 | 53. How can you mock dependencies in Node.js tests? 73 | 54. What is the purpose of the `supertest` library? 74 | 55. How do you test asynchronous code in Node.js? 75 | 56. Explain the significance of code coverage in testing. 76 | 77 | ### Database and Data Handling: 78 | 79 | 57. How do you connect Node.js to a MongoDB database? 80 | 58. Describe the role of an Object-Relational Mapping (ORM) in Node.js. 81 | 59. What is the purpose of the `sequelize` library in Node.js? 82 | 60. How can you use the `mongoose` library for schema validation in MongoDB? 83 | 61. Explain the difference between SQL and NoSQL databases. 84 | 62. How do you perform CRUD operations in Node.js with a database? 85 | 63. Describe the purpose of connection pooling in database connections. 86 | 64. What is a transaction, and how can you implement it in Node.js? 87 | 88 | ### Performance Optimization: 89 | 90 | 65. How can you improve the performance of a Node.js application? 91 | 66. Explain the purpose of the `cluster` module in Node.js. 92 | 67. Describe how to implement caching in a Node.js application. 93 | 68. What is the significance of the `--inspect` flag in Node.js? 94 | 69. How do you profile and debug a Node.js application? 95 | 70. Explain the concept of garbage collection in Node.js. 96 | 97 | ### Real-time Applications: 98 | 99 | 71. How can you implement WebSockets in a Node.js application? 100 | 72. Describe the purpose of the `Socket.io` library. 101 | 73. How do you handle real-time updates in a Node.js application? 102 | 74. Explain the concept of server-sent events (SSE) in Node.js. 103 | 75. What is the significance of long polling in real-time applications? 104 | 105 | ### Deployment and DevOps: 106 | 107 | 76. How do you deploy a Node.js application to a production server? 108 | 77. Explain the purpose of process managers like PM2 in Node.js. 109 | 78. What is Docker, and how can you use it with Node.js? 110 | 79. Describe the use of environment variables in a production Node.js application. 111 | 80. How do you monitor the performance of a deployed Node.js application? 112 | 113 | ### Miscellaneous: 114 | 115 | 81. Explain the difference between `process.argv` and `process.env` in Node.js. 116 | 82. How can you use the `child_process` module in Node.js? 117 | 83. Describe the purpose of the `os` module in Node.js. 118 | 84. What is the role of the `url` module in Node.js? 119 | 85. How do you handle file operations in Node.js? 120 | 86. Explain the purpose of the `events` module in Node.js. 121 | 87. Describe the use of the `fs` module for file system operations. 122 | 88. How can you implement authentication using JSON Web Tokens (JWT) in Node.js? 123 | 89. What is the purpose of the `stream` module in Node.js? 124 | 90. How do you handle cross-platform issues in a Node.js application? 125 | 126 | ### Advanced Concepts: 127 | 128 | 91. Explain the concept of microservices and how it can be implemented in Node.js. 129 | 92. How do you handle memory leaks in a long-running Node.js application? 130 | 93. Describe the purpose of the `async_hooks` module in Node.js. 131 | 94. How can you implement serverless architecture using Node.js? 132 | 95. Explain the concept of GraphQL and how it differs from REST. 133 | 96. How do you implement server-side rendering (SSR) in a Node.js application? 134 | 97. Describe the use of WebAssembly in Node.js. 135 | 98. How can you use the `worker_threads` module for multi-threading in Node.js? 136 | 99. What is the purpose of the `N-API` in Node.js? 137 | 100. Explain the concept of the Node.js event loop phases. 138 | 139 | --------------------------------------------------------------------------------