[Updated] Top 100+ Node Js Interview (MCQ) With Answers - December 2023

Q1. What is Node.js, and what is its primary use?

1. It is used for front-end web development.
2. It is used to build server-side applications.
3. It is used for database management.
4. None of the above.

Q2. How does Node.js handle user requests efficiently despite being single-threaded?

1. It creates a new thread for each request.
2. It uses a multi-threaded architecture.
3. It processes requests asynchronously.
4. It blocks the main thread until a request is complete.

Q3. What are the key features of Node.js?

1. Blocking I/O operations.
2. Single-threaded and non-scalable.
3. Asynchronous and event-driven.
4. Dependent on Python for execution.

Q4. How does Node.js ensure fast code execution, and which JavaScript engine does it use?

1. It uses the V8 JavaScript engine, making code execution faster.
2. It uses a custom JavaScript engine developed by Node.js.
3. It relies on the user's web browser's JavaScript engine.
4. It does not execute JavaScript code.

Q5. What is the main difference between using Node.js and linking HTML and writing JavaScript?

1. Node.js is only used for front-end development, while linking HTML and writing JavaScript is for back-end development.
2. Node.js is a runtime environment for executing JavaScript on the server-side, while linking HTML and writing JavaScript is for executing code on the client-side in a web browser.
3. There is no significant difference; both approaches are interchangeable.
4. Node.js is used for writing client-side scripts, while linking HTML is used for server-side scripting.

Q6. How does Node.js manage I/O operations without blocking the main thread?

1. It blocks the main thread until I/O operations complete.
2. It creates a new thread for each I/O operation.
3. It handles I/O operations asynchronously.
4. It does not support I/O operations.

Q7. What is the role of the event loop in Node.js, and how does it work?

1. It blocks incoming events until the main thread is available.
2. It processes events sequentially in a single thread.
3. It invokes callback functions for events asynchronously.
4. It creates a new thread for each event.

Q8. What is the significance of using the V8 JavaScript Runtime engine?

1. It makes code execution slower due to engine limitations.
2. It uses a custom JavaScript engine for better performance.
3. It relies on the user's web browser for JavaScript execution.
4. It enhances code execution speed and efficiency.

Q9. Why is JavaScript commonly used in Node.js development, and what advantages does it offer?

1. JavaScript is used for front-end development only.
2. JavaScript is not well-suited for server-side programming.
3. JavaScript allows for code sharing between client and server.
4. JavaScript is not widely known among developers.

Q10. How does Node.js handle long-running tasks while maintaining responsiveness to incoming requests?

1. It blocks incoming requests until long-running tasks complete.
2. It creates a separate thread for each long-running task.
3. It performs long-running tasks asynchronously using worker threads or external processes.
4. It does not support long-running tasks.

Q11. Can you explain why Node.js does not buffer data and how it handles data output?

1. Node.js buffers all data to improve performance.
2. Node.js does not handle data output.
3. Node.js outputs data in chunks and does not buffer it.
4. Node.js buffers data and processes it sequentially.

Q12. How does Node.js handle long-running tasks while maintaining responsiveness to incoming requests?

1. It performs long-running tasks asynchronously using worker threads or external processes.
2. It blocks incoming requests until long-running tasks complete.
3. It creates a separate thread for each long-running task.
4. It does not support long-running tasks.

Q13. What is the primary benefit of using Node.js for real-time applications, such as chat applications or online gaming?

1. Node.js is not suitable for real-time applications.
2. Node.js offers high latency for real-time communication.
3. Node.js can only handle static content delivery.
4. Node.js provides low latency and rapid data exchange for real-time applications.

Q14. How does Node.js maintain a responsive main thread while handling multiple concurrent connections?

1. It creates a new thread for each connection.
2. It uses a multi-threaded architecture.
3. It blocks the main thread until connections are complete.
4. It handles connections asynchronously, allowing the main thread to remain responsive.

Q15. How does Node.js handle CPU-intensive tasks while maintaining its non-blocking nature?

1. It blocks incoming requests until CPU-intensive tasks complete.
2. It performs CPU-intensive tasks asynchronously using worker threads or external processes.
3. It creates multiple threads for CPU-intensive tasks.
4. It does not support CPU-intensive tasks.

Q16. Node.js code snippet to print "Hello, Node.js!" to the console.

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

1. There's an error in the code.
2. The code snippet correctly prints "Hello, Node.js!" to the console.
3. The code snippet prints "Hello, World!" instead.
4. The code snippet will result in an infinite loop.

Q17. What are the advantages of using Node.js for building real-time chat applications?

1. Node.js provides low latency, scalability, and event-driven architecture for real-time chat applications.
2. Node.js is not suitable for real-time chat applications.
3. Node.js offers high latency for real-time communication.
4. Node.js can only be used for static content delivery.

Q18. What is the main advantage of Node.js when it comes to handling multiple concurrent connections?

1. It creates a new thread for each connection.
2. It blocks incoming connections until previous ones are complete.
3. It handles connections asynchronously, allowing the main thread to remain responsive.
4. It relies on external libraries to manage connections.

Q19. How does Node.js ensure that event handling does not block the main thread?

1. It blocks the main thread until events are complete.
2. It creates a separate thread for each event.
3. It relies on external libraries for event handling.
4. It processes events in the event loop asynchronously, invoking callback functions when events are ready.

Q20. Why is it important for Node.js to handle I/O operations asynchronously, and how does it achieve this efficiency?

1. Handling I/O operations synchronously improves performance.
2. Handling I/O operations asynchronously ensures the main thread remains responsive.
3. Node.js does not handle I/O operations.
4. Node.js relies on external libraries for I/O operations.

Q21. What is the syntax for creating single-line and multi-line comments in Node.js?

1. Single-line comments start with '#', and multi-line comments are enclosed in ''.
2. Single-line comments start with '//' or '#', and multi-line comments are enclosed in '/*' and '*/'.
3. Single-line comments start with '--', and multi-line comments are enclosed in '//'.
4. Node.js does not support comments.

// This is a single-line comment in Node.js
const a = 'Hello';

/*
This is a
multi-line comment
in Node.js
*/
const b = 'World';

Q22. What is the primary benefit of Node.js's non-blocking (asynchronous) I/O model?

1. It simplifies error handling.
2. It allows for parallel processing of requests.
3. It reduces the need for event-driven programming.
4. It enforces a strict single-threaded execution model.

Q23. How does Node.js handle concurrency, and what is its advantage in this regard?

1. Node.js uses multi-threading for concurrency.
2. Node.js creates a new process for each concurrent request.
3. Node.js handles concurrency through event-driven, single-threaded architecture, which is memory-efficient and scalable.
4. Node.js relies on external libraries for concurrency management.

Q24. What are the advantages of using Node.js for building RESTful APIs compared to traditional server-side technologies?

1. Node.js does not support the development of RESTful APIs.
2. Node.js offers better performance but lacks scalability.
3. Node.js provides high performance, scalability, and a unified JavaScript ecosystem for both front-end and back-end development.
4. Node.js is limited to building SOAP APIs.

Q25. How does Node.js handle memory consumption, and why is it considered memory-efficient?

1. Node.js consumes excessive memory, making it memory-intensive.
2. Node.js relies on garbage collection for memory management.
3. Node.js uses a small, fixed amount of memory per connection and recycles memory efficiently.
4. Node.js has no memory management capabilities.

Q26. Explain the concept of callback functions in Node.js and how they contribute to asynchronous programming.

1. Callback functions are not used in Node.js.
2. Callback functions are used for blocking I/O operations in Node.js.
3. Callback functions are functions passed as arguments to other functions, allowing them to be executed later when an operation is completed, facilitating asynchronous programming.
4. Callback functions are used for defining variables in Node.js.

Q27. "event-driven" in Node.js and why it is important for scalability?

1. Node.js is not event-driven.
2. Event-driven means that Node.js only supports events related to user interactions.
3. Event-driven means that Node.js responds to events, such as incoming requests or data, by invoking appropriate callback functions. This allows for efficient and scalable handling of multiple concurrent events.
4. Event-driven implies that Node.js relies on external event-handling libraries.

Q28. Difference between traditional server-side technologies and Node.js in terms of handling multiple concurrent connections?

1. Traditional technologies use multiple threads for each connection, while Node.js uses a single thread.
2. Traditional technologies use a single thread, while Node.js creates a new thread for each connection.
3. Both traditional technologies and Node.js use a single thread for all connections.
4. Neither traditional technologies nor Node.js support concurrent connections.

Q29. How does Node.js ensure that long-running tasks do not block the main thread, and what is the benefit of this approach?

1. Node.js pauses the main thread until long-running tasks are complete, ensuring task completion.
2. Node.js creates a new thread for each long-running task to avoid blocking the main thread.
3. Node.js splits long-running tasks into smaller asynchronous operations, allowing the main thread to handle other tasks in the meantime, ensuring responsiveness.
4. Node.js does not support long-running tasks.

Q30. What is the primary advantage of using an event-driven architecture in Node.js, especially for real-time applications?

1. An event-driven architecture reduces CPU usage.
2. An event-driven architecture simplifies error handling.
3. An event-driven architecture provides low latency and scalability for real-time applications by efficiently managing asynchronous events.
4. An event-driven architecture is not suitable for real-time applications.

Q31. Why is Node.js considered highly scalable despite its single-threaded nature?

1. It creates multiple threads for handling requests.
2. It blocks requests until previous ones are complete.
3. It processes requests sequentially.
4. It handles requests asynchronously, allowing it to scale.

Q32. Purpose of the Node.js setup process

1. To uninstall Node.js.
2. To configure NPM.
3. To install and configure Node.js for development or server-side applications.
4. To update system drivers.

Q33. What is the role of the "npm install" command

1. It is used to create a new Node.js project.
2. It is used to install Node.js itself.
3. It is used to install project dependencies listed in the "package.json" file.
4. It is used to run JavaScript code in the browser.

Q34. What is the difference between local and global installation of Node.js packages?

1. Local installation installs packages globally on your system, while global installation installs them within a specific project directory.
2. Local installation installs packages within a specific project directory, while global installation installs them globally on your system.
3. Local installation and global installation are the same; they both install packages within a specific project directory.
4. Local installation and global installation are the same; they both install packages globally on your system.

Q35. What is the role of the NPM in Node.js?

1. NPM is used for front-end development only.
2. NPM is not essential for Node.js development.
3. NPM simplifies package management, dependency tracking, and distribution of Node.js modules.
4. NPM is used exclusively for server-side programming.

Q36. How can you check if Node.js is already installed on your system?

1. Run "node --check" in the terminal.
2. Check the system control panel.
3. Inspect the browser settings.
4. Run "node -v" in the terminal.

Q37. What is NPM, and why is it important in Node.js development?

1. NPM is a tool for managing network profiles.
2. NPM is a Node.js programming module.
3. NPM is a package manager for Node.js that simplifies dependency management and project workflows.
4. NPM is a web browser extension.

Q38. How can you install Node.js and NPM on your system?

1. By downloading the Node.js installer from the official website and following the installation instructions for your operating system.
2. By downloading and running the "npm" command.
3. By using a web browser to access Node.js files.
4. By manually copying Node.js files to your system.

Q39. What is the recommended way to manage multiple versions of Node.js on your system?

1. By manually renaming Node.js installation folders.
2. By using a package manager other than NPM.
3. By using a version manager like "nvm" (Node Version Manager) for Unix-based systems or "nvm-windows" for Windows.
4. By creating separate user accounts for each Node.js version.

Q40. What is the role of the Node.js Package Manager (NPM) during the setup process?

1. NPM manages the Node.js source code.
2. NPM helps install Node.js itself.
3. NPM is not essential for Node.js development.
4. NPM is used to manage project dependencies and libraries, making it crucial for Node.js development.

Q41. What are the potential advantages of using a version manager like "nvm" for Node.js installation and management?

1. Version managers are not recommended for Node.js.
2. Version managers allow you to switch between different Node.js versions easily and manage multiple versions concurrently.
3. Version managers are only useful for web development, not server-side applications.
4. Version managers are less stable than direct Node.js installations.

nvm install 14.17.0   # Install Node.js version 14.17.0
nvm use 14.17.0       # Switch to Node.js version 14.17.0
nvm install 16.3.0    # Install Node.js version 16.3.0
nvm use 16.3.0        # Switch to Node.js version 16.3.0

Q42. How can you update Node.js to a newer version once it's already installed on your system using NPM?

1. Use the "npm update node" command.
2. Node.js cannot be updated using NPM.
3. Run "npm install -g npm" to update Node.js and NPM to their latest versions.
4. Manually download and install the new Node.js version from the official website.

Q43. What is the purpose of the "node" command in Node.js?

1. It is used for creating new Node.js projects.
2. It is used to install Node.js on your system.
3. It is used to run JavaScript files and execute JavaScript code on the server-side.
4. It is used for managing project dependencies.

node myScript.js

Q44. When setting up a Node.js project, what is the purpose of the "package.json" file?

1. It is used for storing project documentation.
2. It is used to define metadata about the project, including its name, version, dependencies, and scripts.
3. It is used for storing test cases and unit tests.
4. It is used for configuring server settings.

{
	"name": "my-node-project",
	"version": "1.0.0",
	"description": "A sample Node.js project",
	"main": "index.js",
	"scripts": {
	"start": "node index.js",
	"test": "mocha"
	},
	"dependencies": {
	"express": "^4.17.1",
	"lodash": "^4.17.21"
	},
	"devDependencies": {
	"mocha": "^9.0.0"
	},
	"author": "Your Name",
	"license": "MIT"
}

Q45. How can you specify the Node.js version required for your project in the "package.json" file, and why is this important?

1. Specify the version in the "scripts" section of "package.json" to ensure compatibility.
2. Specify the version in the "engines" field of "package.json" to ensure compatibility.
3. Specify the version in the "dependencies" section of "package.json" to ensure compatibility.
4. Specify the version in the "name" field of "package.json" to ensure compatibility.

Q46. What is the purpose of the "node_modules" directory in a Node.js project?

1. It's a directory for Node.js documentation.
2. It's where Node.js stores configuration files.
3. It stores all the installed dependencies for a Node.js project, allowing the project to use external libraries and modules.
4. It's a temporary directory created during Node.js installation.

Q47. What is the role of the "npx" command in Node.js?

1. The "npx" command is used to create new Node.js projects.
2. The "npx" command is used to install Node.js modules globally.
3. The "npx" command is used to execute Node.js packages or binaries without the need for global installation, ensuring that the latest versions are used.
4. The "npx" command is used for managing project dependencies.

npx create-react-app my-app

Q48. How can you create a new Node.js project using the "npm init" command?

1. The "npm init" command creates a new project and automatically generates all required configuration files.
2. The "npm init" command prompts you to provide information such as the project name, version, description, entry point, test command, and repository URL.
3. The "npm init" command creates a new project with default settings, and you can manually edit the configuration files later.
4. The "npm init" command is not used for creating new Node.js projects.

Q49. What is the purpose of the "package-lock.json" file in a Node.js project, and how does it differ from "package.json"?

1. The "package-lock.json" file is used for storing user authentication data.
2. The "package-lock.json" file is an autogenerated file that keeps track of the exact versions of dependencies installed in a project, ensuring consistent installations across different environments.
3. The "package-lock.json" file is used for defining project metadata.
4. The "package-lock.json" file is a backup of the "package.json" file.

Q50. How can you globally install a Node.js package or tool using the "npm install -g" command?

1. The "npm install -g" command is used for installing project-specific dependencies.
2. The "npm install -g" command is used to uninstall Node.js packages globally.
3. The "npm install -g" command installs a Node.js package or tool globally on the system, making it accessible from the command line. This approach is typically used for installing command-line tools or utilities that you want to use across different projects.
4. The "npm install -g" command is not a valid npm command.

Q51. What is the purpose of the "NODE_ENV" environment variable in Node.js?

1. The "NODE_ENV" variable is used to specify the location of Node.js installations on a system.
2. The "NODE_ENV" variable is used to set the current working directory for a Node.js application.
3. The "NODE_ENV" variable is used to indicate the environment in which a Node.js application is running, such as "development," "production," or "testing." It can be used to configure different behaviors or settings based on the environment.
4. The "NODE_ENV" variable is used for internal debugging purposes and should not be modified.

if (process.env.NODE_ENV === 'production') {
    // Production error handling
    app.use((err, req, res, next) => {
    res.status(500).send('Something went wrong');
    });
} else {
    // Development and other environment error handling
    app.use((err, req, res, next) => {
    res.status(500).send(err.stack);
    });
}

Q52. What category do data types like String, Number, and Boolean belong to in Node.js?

1. Primitives
2. Objects

var name = "John"; // String
var age = 30; // Number
var isTrue = true; // Boolean

Q53. Which of the following is a primitive data type in Node.js?

1. Array
2. Function
3. Symbol

const uniqueSymbol = Symbol('unique');

Q54. Which category of data types includes Function and Array in Node.js?

1. Primitives
2. Objects

function greet() {
    console.log("Hello!");
}
    
const numbers = [1, 2, 3, 4];

Q55. What data type in Node.js can hold a large integer value?

1. String
2. Number
3. BigInt

const bigIntValue = 1234567890123456789012345678901234567890n;

Q56. Which data type in Node.js represents a variable that has not been assigned a value yet?

1. Undefined
2. Null
3. Symbol

let uninitializedVariable;
console.log(uninitializedVariable); // Outputs: undefined

Q57. What is a String in Node.js?

1. A sequence of numeric values
2. A sequence of Unicode characters that can be wrapped in single or double quotation marks
3. A special data type used only for dates and times
4. An array of characters

const myString = "Hello, Node.js!";

Q58. Which function is used to split a string and return an array of strings?

1. charAt()
2. Concat()
3. Match()
4. Split()

const myString = "apple,banana,cherry";
const fruitsArray = myString.split(",");

console.log(fruitsArray); // Output: ["apple", "banana", "cherry"]
console.log(myString);    // Output: "apple,banana,cherry"

Q59. Which function is used to get the character at a specific index in a string?

1. Concat()
2. charAt()
3. indexOf()
4. Match()

const myString = "Node.js";

console.log(myString.charAt(1));    // Output: "o" (character at index 1)
console.log(myString.charAt(10));   // Output: "" (no character at index 10, so an empty string is returned)
console.log(myString.charAt(-1));   // Output: "" (no character at index -1, so an empty string is returned)

Q60. Which function is useful to join an array of strings separated by a comma (,) operator?

1. Split()
2. Concat()
3. Match()
4. Join()

const fruits = ["apple", "banana", "cherry"];

// Use the join method to join array elements with an empty separator
const result = fruits.join("");
console.log(result); // Output: "applebananacherry"

// Use the join method to join array elements with a comma separator
const result1 = fruits.join(",");
console.log(result1); // Output: "apple,banana,cherry"

Q61. What is the output of the following code?

const str = "Node.js";
console.log(str.charAt(7));

1. ""
2. "Node.js"
3. Error
4. "s"

Q62. Which function should you use to concatenate two strings without spaces in Node.js?

1. str.concat()
2. str.join()
3. str.concat('')
4. str.splice()

Q63. What is the output of the following code in Node.js?

const str = "apple,banana,cherry";
const result = str.split(",");
console.log(result.length);

1. 3
2. 18
3. 1
4. 15

Q64. Which of the following statements is true regarding the `match()` function in Node.js?

1. It always returns an array.
2. It returns the first occurrence of the matched string.
3. It's not a built-in function in Node.js.
4. It returns null if no match is found.

Q65. What is the output of the following code?

const str = "Node.js";
console.log(str.slice(1, -1));

1. "ode.j"
2. "ode."
3. Error
4. Undefined

console.log(str.slice(1, -1));     // Output: "ode.j"
console.log(str.substring(1, -1)); // Output: "N"


The second argument -1 is treated as if it were 0 because negative indices are interpreted as 0.
So, it will extract a substring from index 1 (the second character, "o") to index 0 (the first character, "N").

Q66. What is the output of the following code?

const str = "Node.js";
console.log(str.charAt(-1));

1. "N"
2. Error
3. ""
4. "."

Q67. Which function is used to find the last index of a specific character or substring in a string in Node.js?

1. str.lastIndexOf()
2. str.charAt()
3. str.indexOf()
4. str.search()

Q68. What is the output of the following code?

const str = "apple,banana,cherry";
const result = str.split("a");
console.log(result.length);

1. 5
2. 2
3. 1
4. 4

const str = "apple,banana,cherry";
const result = str.split("a");
console.log(result); // [ '', 'pple,b', 'n', 'n', ',cherry' ]

Q69. What is the output of the following code?

const str = "Node.js";
console.log(str.lastIndexOf("o", 1));

1. 0
2. 1
3. -1
4. 3

const str = "Node.js Node.js";
console.log(str.lastIndexOf("o"));    // Output: 9 (index of the last "o" in the string)
console.log(str.lastIndexOf("o", 0)); // Output: -1 (searching before the start of the string, so not found)
console.log(str.lastIndexOf("o", 1)); // Output: 1 (searching from index 1, which is the second character "o")
console.log(str.lastIndexOf("o", 2)); // Output: 1 (searching from index 2, which is still the second character "o")
console.log(str.lastIndexOf("o", 3)); // Output: 1 (searching from index 3, which is still the second character "o")
console.log(str.lastIndexOf("z"));    // Output: -1 (the letter "z" is not in the string)
console.log(str.lastIndexOf("z", 1)); // Output: -1 (searching from index 1, but the letter "z" is not in the string)

Q70. What is the output of the following code?

const str = "Node.js";
console.log(str.lastIndexOf("o"));

1. 0
2. 1
3. 4
4. -1

Q71. Which of the following functions is used to find the index of a specific character in a string?

1. Concat()
2. charAt()
3. indexOf()
4. Split()

const myString = "Hello, Node.js!";
const index = myString.indexOf("Node");
console.log(index) //7

Q72. Which function is useful to match multiple strings?

1. Concat()
2. charAt()
3. Match()
4. indexOf()

const text = "Hello, Node.js!";
const pattern = /Node.js/;
const result = text.match(pattern);
console.log(result[0]); //Node.js
console.log(result); // [ 'Node.js', index: 7, input: 'Hello, Node.js!', groups: undefined ]

Q73. Which function is used to find the index of the first occurrence of a specific character or substring in a string in Node.js?

1. str.lastIndex()
2. str.firstIndex()
3. str.indexOf()
4. str.search()

const str = "Hello, world! Welcome to Node.js";
const indexOfWorld = str.indexOf("world");
console.log(indexOfWorld); // Output: 7
console.log("Original String:", str); // Output: Original String: Hello, world! Welcome to Node.js
console.log("Substring:", str.substring(indexOfWorld, indexOfWorld + 5)); // Output: Substring: world!
console.log("Substring Length:", str.substring(indexOfWorld, indexOfWorld + 5).length); // Output: Substring Length: 6
console.log("Character at Index 0:", str.charAt(0)); // Output: Character at Index 0: H
console.log("Character at Index 7:", str.charAt(7)); // Output: Character at Index 6: w

Q74. What is the output of the following code?

const str = "Node.js";
console.log(str.substring(2, -1));

1. Error
2. "No"
3. Undefined
4. "ode"

Q75. Which function is used to join an array of strings separated by a specific character in Node.js?

1. str.concat()
2. str.split()
3. str.join()
4. str.merge()

Q76. Which function is used to check if a string starts with a specified substring in Node.js?

1. str.startsWith()
2. str.substring()
3. str.contains()
4. str.firstIndexOf()

const str = "Hello, World!";
const substring = "Hello";

if (str.startsWith(substring)) {
    console.log("The string starts with the specified substring.");
} else {
    console.log("The string does not start with the specified substring.");
}

Q77. Which function is used to replace a specified substring with another string in Node.js?

1. str.replace()
2. str.replaceAll()
3. str.update()
4. str.modify()

Q78. What will be the output of the following code snippet?

const str = "Node.js Node.js";
console.log(str.indexOf("o", 0));  
console.log(str.lastIndexOf("o", 0));

1. 10 -1
2. 10 1
3. 1 0
4. 1 -1

const str = "Node.js Node.js";

console.log(str.indexOf("N"));         // Output: 0 (index of the first occurrence of "N" in the string)
console.log(str.lastIndexOf("N"));     // Output: 8 (index of the last occurrence of "N" in the string)
console.log(str.indexOf("n"));         // Output: -1 (no occurrence of lowercase "n" in the string)
console.log(str.lastIndexOf("n"));     // Output: -1 (no occurrence of lowercase "n" in the string)

console.log(str.indexOf("N", 1));      // Output: 8 (searching for "N" starting from index 1, finds it at index 8)
console.log(str.lastIndexOf("N", 1));  // Output: 0 (searching for "N" starting from index 1, finds it at index 0)

console.log(str.indexOf("N", 10));     // Output: -1 (no "N" found starting from index 10)
console.log(str.lastIndexOf("N", 10)); // Output: 8 (searching for "N" starting from index 10, finds it at index 8)

console.log(str.indexOf("Z", 1));      // Output: -1 ("Z" is not in the string)
console.log(str.lastIndexOf("Z"));     // Output: -1 ("Z" is not in the string)

Q79. What will be the output of the following JavaScript code snippet?

const str = "JavaScript";
console.log(str.slice(-4, -1));     // Output: ?
console.log(str.substring(-4, -1)); // Output: ?

1. Output: "scr", Output: "scr"
2. Output: "rip", Output: ""
3. Output: "rip", Output: "scr"
4. Output: "", Output: ""

const str = "JavaScript";
console.log(str.slice(2, 5));       // Output: "vaS"
console.log(str.substring(2, 5));   // Output: "vaS"
console.log(str.slice(2));          // Output: "vaScript" 
console.log(str.substring(2));      // Output: "vaScript" 
console.log(str.slice(-3));         // Output: "ipt" 
console.log(str.substring(-3));     // Output: "JavaScript"
console.log(str.slice(5, 2));       // Output: "" 
console.log(str.substring(5, 2));   // Output: "vaS"

Q80. Which function is used to convert a string to lowercase in Node.js?

1. str.toLowerCase()
2. str.toLower()
3. str.lowerCase()
4. str.convertToLower()

Q81. What is the output of the following code?

const str = "Node.js";
console.log(str.includes("node"));

1. true
2. false
3. Error
4. Undefined

Q82. What is the purpose of the "concat()" function in Node.js?

1. To split a string into an array
2. To match multiple strings
3. To join multiple strings together
4. To find the index of a specific character in a string

const str1 = "Hello";
const str2 = "Node.js";
const result = str1.concat(", ", str2);
console.log(result) // Hello, Node.js

Q83. What is the data type of numbers in Node.js?

1. Integer
2. Float
3. 64 bits floating point number
4. Double

const num1 = 10;
const num2 = 20;
console.log(`sum: ${num1 + num2}`); // sum: 30

Q84. Which functions are used to convert a string to a number in Node.js?

1. toNumber() and toInt()
2. int() and float()
3. parseInt() and parseFloat()
4. convertToInt() and convertToFloat()

console.log(parseInt("32"));  // 32
console.log(parseFloat("8.24")); // 8.24

Q85. What is the result of parseInt("234.12345")?

1. 234.12345
2. 234
3. NaN
4. 123.45

console.log(parseInt("234.12345")); // 234

Q86. What is the output of isFinite(10/5)?

1. true
2. false
3. 10
4. NaN

console.log(isFinite(10/5)); // true

Q87. What does the expression 5 / 0 return?

1. 0
2. Infinity
3. NaN
4. -Infinity

console.log(5 / 0); // Infinity
console.log(-5 / 0); // -Infinity

Q88. What is the primary advantage of using parseInt() over parseFloat()?

1. parseInt() always returns an integer.
2. parseFloat() is deprecated in Node.js.
3. parseInt() handles decimal values more accurately.
4. parseFloat() converts strings to numbers more efficiently.

console.log(parseInt("32"));  // 32

Q89. What does the function isFinite(10/0) return?

1. true
2. false
3. Infinity
4. NaN

console.log(isFinite(10/0)); // false

Q90. What is the purpose of the parseFloat() function?

1. To convert a string to an integer
2. To convert a string to a floating-point number
3. To check if a number is finite
4. To round a number to the nearest integer

console.log(parseFloat("8.24")); // 8.24

Q91. What is the output of parseInt("42px")?

1. 42
2. 42px
3. NaN
4. 0

console.log(parseInt("42px")); // 42

Q92. Which of the following functions can be used to check if a number is finite?

1. isFinite()
2. isNaN()
3. parseFloat()
4. parseInt()

console.log(isFinite(10/5)); // true

Q93. What is a BigInt value in Node.js?

1. A small integer
2. An integer followed by 'n'
3. A floating-point number
4. An integer with a decimal point

const maxSafeInteger = 99n;
console.log(maxSafeInteger); //99n

Q94. How can you create a BigInt in Node.js using the BigInt() function?

1. By appending 'n' to an integer literal
2. By using the new operator with an integer value
3. By calling the BigInt() function with an integer or string value (without the new operator)
4. By using parseFloat() with a number

const num2 = BigInt('99'); // This is equivalent

Q95. What is the typeof a BigInt value in Node.js?

1. integer
2. float
3. bigint
4. string

let check=10n;
console.log(typeof(check)) //bigint

Q96. Which of the following is NOT a valid way to create a BigInt?

1. const num = 42n;
2. const num = BigInt(42);
3. const num = BigInt('42');
4. const num = 42.0n;

Q97. What is the purpose of using BigInts?

1. To represent floating-point numbers
2. To perform precise integer arithmetic beyond the limits of JavaScript's Number type
3. To create strings
4. To store boolean values

Q98. What are the possible values of the Boolean data type in Node.js?

1. true and false
2. 1 and 0
3. yes and no
4. string and number

const isValid = true;

Q99. Which function is used to convert any data type to a boolean value?

1. toBoolean()
2. bool()
3. Boolean()
4. convertToBoolean()

const n = 42;
const boolValue = Boolean(n);
console.log(boolValue) // true

Q100. Which of the following values evaluate to false when converted to a boolean?

1. true
2. 1
3. null
4. "false"

const boolValue = Boolean(null);

Q101. What is the result of the expression true && false?

1. true
2. false
3. null
4. undefined

console.log(false && false); // Output: false
console.log(false && true);  // Output: false
console.log(true && false);  // Output: false
console.log(true && true);   // Output: true

console.log(false || false); // Output: false
console.log(false || true);  // Output: true
console.log(true || false);  // Output: true
console.log(true || true);   // Output: true

Q102. What is the result of the expression !true in Node.js?

1. true
2. false
3. null
4. undefined

console.log(!true); // false

Q103. What is the value of `result` in the following code?

const isValid = false;
const result = isValid ? "Yes" : "No";

1. "Yes"
2. "No"
3. true
4. false

Q104. What is the result of the following expression?

const num1 = 42;
const num2 = 0;
const result = num1 && num2;

1. true
2. false
3. 0
4. 42

Q105. What is the typeof a BigInt value in Node.js?

const bigIntValue = 123n;

1. integer
2. float
3. bigint
4. string

Q106. What is the output of the following code?

const num = 42n;
console.log(num + 1n);

1. 43
2. 43n
3. 42n1
4. Error

Q107. What is the value of the variable "z" in the following code?

Consider the following code:

let z;
console.log(z);

1. Undefined
2. null
3. 0
4. NaN

Q108. What value does a variable take if it is assigned a null value?

1. 0
2. null
3. undefined
4. false

let y = null;
console.log(y); // null

Q109. What will be the output of the following code snippet?

Consider the following code:

let a = null;
let b = undefined;
console.log(typeof a === typeof b);

1. true
2. false
3. null
4. undefined

let a = null;
let b = undefined;
console.log(typeof a ); //object
console.log(typeof b ); //undefined
console.log(typeof a == typeof b); //false
console.log(typeof a === typeof b); //false

Q110. What does the following code snippet print?

Consider the following code:

let x = null;
let y = undefined;
console.log(x == y);

1. true
2. false
3. null
4. undefined

let x = null;
let y = undefined;
console.log(x === y); //false
console.log(x == y); //true
console.log(typeof x); //object
console.log(typeof y); //undefined

Q111. What is the purpose of the "Symbol" data type in Node.js?

1. To represent unique and immutable values
2. To create mutable variables
3. To store numeric values
4. To define functions

const NAME = Symbol();
const person = {
  [NAME]: 'India'
};
console.log(person[NAME]); // 'India'

Q112. What is a Symbol in Node.js?

1. A mutable primitive value
2. An immutable primitive value that is unique
3. An object with a private value
4. A string with special characters

const NAME = Symbol()

Q113. What is the main characteristic of a Symbol in Node.js?

1. It can be modified after creation
2. It is not unique and can have duplicate values
3. It is an object with public visibility
4. It is immutable and unique

Q114. How do you create a Symbol in Node.js?

1. Using curly braces
2. By defining a string
3. By calling the Symbol() function
4. By using special characters

const NAME = Symbol()

Q115. What is the purpose of a Symbol in Node.js?

1. To store public data
2. To represent special characters in strings
3. To create duplicate values
4. To create unique property keys for objects

// Creating a symbol
const mySymbol = Symbol("mySymbol");

// Creating an object with a symbol property
const myObject = {
  [mySymbol]: "This is a symbol property",
};

// Accessing the symbol property
console.log(myObject[mySymbol]); // Output: 'This is a symbol property'