Top 10 Node JS Interview Questions and Answers in 2020

There is no second thought that the open source, advanced server environment of Node.JS is extremely popular, and one of the most globally used client-side programming languages with countess rewarding career opportunities for developers of all experience. We would suggest you follow further to find top Node JS interview questions with expert suggested best answers for your practice. Practicing with this set of most asked tech interview questions will definitely increase your chance of success to the maximum for upcoming interview sessions, no matter the level of experience you have.

So, let’s continue with our top 10 Node.JS interview questions and suggested answers for your acknowledgment. More importantly, these questions are way different from the traditional ones and suits best the modern approach of employers.

1. How good is Node.JS with application scalability?

Easy scalability is one of the key advantages that developers will receive while using Node.JS. Here, developers will find it extremely relevant to scale their applications in vertical as well as horizontal directions. With the inclusion of additional nodes to the existing system, applications here can be scaledin a horizontal manner. Node.JS also permits developers to add extra resources to single nodes while vertically scaling the application. Undoubtedly, Node.JS is highly salable compared to other JavaScript servers.

2. Can we use Node.JS as a single programming language?

Yes, Node.JS can be used as a single programming language. As it offers the luxury to write the server-side application in JavaScript, developers here will be able to write both the front-end as well as back-end application in JavaScript with the use of run time environment. This also makes the webs application deployment simpler because of JavaScript’s huge line-up of browser support.

3. What is the benefit of Node.JS as a full-stack JavaScript?

Node.JS can be used as a full-stack JavaScript to serve the purpose of both server-side and client-side application. Therefore, employers don’t have to hire separate developers for front-end and back-end development;This will save valuable time, money,and man power for businesses.

4. How does Node.JS work with caching?

Node.JS’ sopen-source run time environment offers the feature of caching for single modules. Whenever the first module receives a request, it automatically gets cached in the application memory. We don’t have to re-execute the codes as caching will allow applications to load web pages faster and respond more optimally to the users.

5. How can Node.JS multiple requests simultaneously?

Due to the availability of non-blocking I/O systems, Node.JS can handle multiple requests simultaneously with perfection. This system can handle the request of concurrent handling better compared other competitors, including Python and Ruby. Here incoming requests get properly lined up and executed fast and systematically.

For more advanced Node.JS interview questions, please visit here.

6. What is a Node.JS eventsmodule?

Event is a built-in Node.JS module, where developers can create, fire, and listen for their own events. It uses the require() method.

7. How can you avoid callback hells?

We can avoid callback hell by different available solutions,as mentioned below.

Promises: The promise is s result of an asynchronous operation.We can create a promise on these three states:

· Pending: When the initial state is not fulfilled or rejected.

· Fulfilled: When the operation gets completed successfully.

· Rejected: When the operation gets failed.


These are functions which can be resumed and paused. It doesn’t get executed immediately when called. Instead,it returns a generator object or generator object with which we can control the execution of the function.

8. What are Promises and how you can use it?

In Node.JS, promises are objects representing the completion or failure of an asynchronous operation. It can be created in JavaScript code and returned from anode package present externally. The promises that perform async operations can call anyone these two methods; reject or resolve. The user should take care of the code logic to determine when and where to call these functions. With the successful operation, pass the data to the code uses that promise, or just pass error. The code that uses a promise should use the then function on that specific promise, which will take two anonymous functions as parameters.

9. What is the use of module.exports in Node.js?

In Node.JS, module. exportsis a special object that is included in every JavaScript file present in the Node.JS file default. Here module is a variable that represents the current module,and export is the object that will be exposed as the module.

10. How we can use async and await in node js?


With the use of a sync before a function, our function will always return a promise. Even if your function returns a non-promise value, adding the function definition with the keyword a sync will direct JavaScript to automatically wrap that value and resolve the promise.


async function f() {

return 1;



With the use of await, the JavaScript will wait until the promise is settled and returns the value.


// works only inside async functions

let value = await promise;

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