Tenmiles – Node JS Interview Questions

Here is the list of Node JS Interview Questions which are recently asked in Tenmiles company. These questions are included for both Freshers and Experienced professionals. Our Node JS Training has Answered all the below Questions.

1. Why use Node.js?

Node.js is used for non-blocking, event-driven servers because of its single-threaded nature. It's used for traditional web sites and back-end API services, but was designed with real-time, push-based architectures in mind.

2. What are the features of Node.js?

Asynchronous and Event Driven − All APIs of Node.js library are asynchronous, that is, non-blocking.
ery Fast -, Node.js library is very fast in code execution.
Single Threaded but Highly Scalable − Node.js uses a single threaded model with event looping.
No Buffering − Node.js applications never buffer any data.
License

3. How do you update NPM to a new version in Node.js?

To check the NPM version use npm version or node --version . If you prefer CLI, to update NPM use npm install -g npm and then npm install -g node.

4. Why is Node.js Single-threaded?

Node.js is single-threaded similar to JavaScript but not purely JavaScript code which implies things that are done asynchronously like network calls, file system tasks, DNS lookup, etc.

5. Explain callback in Node.js.

Node.js is an asynchronous platform, doesn't wait around for things like file I/O to finish - Node. js uses callbacks. A callback is a function called at the completion of a given task; this prevents any blocking, and allows other code to be run in the meantime.

6. What is callback hell in Node.js?

A promise is a returned object from any asynchronous function, to which callback methods can be added based on the previous function’s result. It uses then() method to call async callbacks. We can chain as many callbacks as we want and the order is also strictly maintained.

Use fetch () method to fetch an object from the network. It also uses catch () method to catch any exception when any block fails.

7. Name the types of API functions in Node.js.

The types of API functions in Node.js are Asynchronous, Non-blocking functions, Synchronous, blocking functions.

8. What are the functionalities of NPM in Node.js?

NPM provides online repositories for node. js packages/modules which are searchable on search.nodejs.org. It provides command line utility to install Node.js packages, do version management and dependency management of Node.js packages.

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9. Explain What is NPM ?

NPM-Node Package Manager) is a package manager for the JavaScript programming language which consists of a command line client, also called npm and an online database of public and paid-for private packages, called the npm registry.

10. Explain Modules in Node Js ?

Modules are the blocks of encapsulated code that communicates with an external application on the basis of their related functionality. It can be a single file or a collection of multiples files/folders Node. js Core Modules. The few core modules of Node.js are

http - http module includes classes, methods and events to create Node.js http server.
url - url module includes methods for URL resolution and parsing

11. What are CommonJs Modules ?

Common JS module is a reusable piece of JavaScript that exports specific objects made available to any dependent code. Unlike AMD, there are typically no function wrappers around such modules.

12. For what require() is used in Node Js ?

require() is used to consume modules that allows to include modules in the application. You can add built-in core Node. js modules, community-based modules (node_modules), and local modules too.

13. Explain module.exports in Node Js ?

An export is a special object which is included in every JavaScript file in the Node. js application by default. The module is a variable that represents the current module, and exports are an object that will be exposed as a module. So, whatever you assign to module.

14. Is Node Js Single-threaded?

Node.js is single-threaded similar to JavaScript but not purely JavaScript code which implies things that are done asynchronously like network calls, file system tasks, DNS lookup, etc

15. What are events ?

Many objects in a Node emit events, for example, a net. Server emits an event each time a peer connects to it, fs. readStream emits an event when the file is opened. All objects which emit events are the instances of events.

16. Explain event loop in Node Js ?

The event loop is what allows Node.js to perform non-blocking I/O operations — despite the fact that JavaScript is single-threaded — by offloading operations to the system kernel whenever possible. Since most modern kernels are multi-threaded, they can handle multiple operations executing in the background.

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TOP MNC's NODE JS INTERVIEW QUESTIONS & ANSWERS

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Tenmiles Node JS Interview Questions