Accenture – Node JS Interview Questions

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

1. What is Node.js? Where can you use it?

Node JS is an open source development platform for executing JavaScript code server-side. It is useful for developing applications that require a persistent connection from the browser to the server and for real-time applications such as chat, news feeds and web push notifications.

It is primarily used for non-blocking, event-driven servers, due to 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. Why use Node.js?

Node JS is easily employed as a server-side proxy where it can handle a large amount of simultaneous connections in a non-blocking manner. It is useful for proxying different services with different response times, or collecting data from multiple source points.

3. What are the features of Node.js?

Features of Node JS

Asynchronous and Event Driven.
Very Fast, Single Threaded but Highly Scalable.
No Buffering.
License.

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

Update Node.
Update npm: To update NPM, use the following command: npm install -g npm.
Check if nvm is installed successfully Open a new terminal nvm -v.
Install latest version of node

5. Why is Node.js Single-threaded?

Node JS was created as an experiment in asynchronous processing and in process on a single thread could provide more performance and scalability under typical web loads than the typical thread-based implementation when the application isn't doing CPU intensive stuff and can runthousands more concurrent connections than Apache or IIS or other thread-based servers.

6. Explain callback in Node.js.

Callback is an asynchronous equivalent for a function and it is called at the completion of a given task. Node makes heavy use of callbacks and makes Node JS highly scalable, as it can process a high number of requests without waiting for any function to return results.

7. What is callback hell in Node.js?

This is a big issue caused by coding with complex nested callbacks. Here, each and every callback takes an argument that is a result of the previous callbacks. In this manner, the code structure looks like a pyramid, making it difficult to read and maintain.

8.How do you prevent/fix callback hell?

Declaring the functions beforehand are one of the best ways to reduce code clutter is by maintaining better separation of code. If you declare a callback function beforehand and call it later, you'll avoid the deeply nested structures that make callback hell so difficult to work with.

9. Explain the role of REPL in Node.js.

The Node JS Read-Eval-Print-Loop (REPL) is an interactive shell that processes Node. The shell reads JavaScript code the user enters, evaluates the result of interpreting the line of code, prints the result to the user, and loops until the user signals to quit. The REPL is bundled with every Node.

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

The two types of API functions in Node JS are: Asynchronous (non-blocking) function and (Synchronous) blocking functions.

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11. Which is the first argument typically passed to a Node.js callback handler?

The first parameter of the callback is the error value. If the function hits an error, then typically call the callback with the first parameter being an Error object. If it cleanly exits, then they will call the callback with the first parameter being null and the rest being the return value(s).

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

Node Package Manager provides two main functionalities:

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

13. What is the difference between Node.js and Ajax?

Node JS is an open-source framework based on JavaScript v8 engine. AJAX is a web development technique for making asynchronous calls to the server. It only works with JavaScript because it is the runtime environment for JavaScript.

14. Explain chaining in Node.js.

Chaining in Node JS can be achieved using the asyncnpm module. There are two most commonly used methods for chaining functions provided by the async module:

parallel(tasks, callback) is a collection of functions that runs parallel in practice through I/O switching
series(tasks, callback)in tasks run only after the previous function is completed

15. What are “streams” in Node.js? Explain the different types of streams present in Node.js.

Readable Stream is used for read operation and Writable Stream is used for write operation. Duplex Stream can be used for both read and write operation. Transform is a type of duplex stream where the output is computed based on input.

16. What are the exit codes in Node.js? List some exit codes.

Exit codes are the specific codes that can be used to end a process. The few examples of exit codes are Uncaught Fatal Exception, Fatal Error, Non-function Internal Exception Handler, Internal Exception handler Run-Time Failure, Internal JavaScript Evaluation Failure, etc.

17. What are Globals in Node.js?

The global object in JavaScript is an always defined object that provides variables and functions, and is available anywhere. In a web browser, the global object is the window object, while it is named global in Node. js. The global object can be accessed using the this operator in the global scope.

18. What is the difference between AngularJS and Node.js?

Angular JS is a front-end framework can be used with any backend programming language like PHP, Java etc., whereas Node JS is simply a server-side language; in a web application like context, it acts as a Java on the server-side. It runs on the client browser, whereas Node JS runs on the server-side.

19. Why is consistent style important, and what tools can be used to assure it?

When working in a team, consistent style is important, so team members can modify more projects easily, without having to get used to a new style each time. Also, it can help eliminate programming issues using static analysis.

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Accenture Node JS Interview Questions