20 Node.js Microservices Interview Questions and Answers

Node.js is a popular open-source platform that can be used to develop server-side applications. When applying for a position that involves Node.js, it is likely that you will be asked questions about microservices. Microservices are a type of software architecture that allows you to break down a large application into smaller, independent services. An understanding of microservices is essential for any developer working with Node.js. In this article, we discuss the most commonly asked questions about Node.js microservices and how you should respond.

Node.js Microservices Interview Questions and Answers

Here are 20 commonly asked Node.js Microservices interview questions and answers to prepare you for your interview:

1. What is Node.js?

Node.js is a JavaScript runtime environment that allows you to run JavaScript code outside of a browser. This makes it ideal for creating server-side applications. Node.js also has a large ecosystem of open-source libraries that can be used to create microservices.

2. How does the event loop work in a Node.js application?

The event loop is the mechanism that Node.js uses to handle asynchronous events. It works by waiting for events to happen, and then triggering the appropriate callback functions to handle those events.

3. Can you explain how to create a simple HTTP server in Node.js?

Creating an HTTP server in Node.js is actually quite simple. All you need to do is use the built-in http module, and call the createServer() method. This method takes a callback function as an argument, which will be called whenever a request is made to the server. The callback function will be passed two arguments: a request object, and a response object. The request object will contain information about the request that was made, while the response object is used to send data back to the client.

Here is a simple example:

var http = require(‘http’);

http.createServer(function(request, response) {
// do something here
}).listen(8080); // listen on port 8080

In this example, we are simply creating a server that will do nothing but listen on port 8080. Of course, you can do much more than this with your server.

4. Why do we need socket programming in Node.js?

Socket programming is important in Node.js because it allows for the real-time exchange of data between a server and its clients. This is important for applications that need to be able to update in real-time, such as chat applications or stock tickers.

5. Is it possible to use Node.js without Express? If yes, then why would someone want to do that?

Yes, it is possible to use Node.js without Express. There are a few reasons why someone might want to do this. The first is that it can simplify the development process by not having to worry about configuring a web server. Additionally, it can make the code more portable and easier to deploy.

6. How do you handle errors when using callbacks in Node.js?

There are a few different ways to handle errors when using callbacks in Node.js. One way is to simply check for the error argument in the callback function and handle it accordingly. Another way is to use the built-in Error object and throw an error if one is encountered.

7. What are some ways you can make your Node.js applications more secure?

There are a few ways to make your Node.js applications more secure:

– Use a secure server framework like Express.js
– Use secure authentication and authorization mechanisms
– Use a secure database like MongoDB
– Use a secure communications protocol like HTTPS

8. What’s the difference between an error-first and normal callback?

An error-first callback is a callback function that takes an error object as its first argument. If the error object is non-null, then it indicates that an error has occurred. Normal callback functions do not have this error-first argument, and instead simply receive the results of the operation as arguments.

9. What do you understand by child processes in Node.js? What are they used for?

Child processes are used in Node.js to spawn new processes. This is often done to create new workers for a cluster, or to run tasks in parallel. Child processes inherit the stdio streams of the parent process, so they can be used to communicate between processes.

10. Can you give me examples of where you might want to spawn a new process?

There are a few reasons you might want to spawn a new process:

– To run a CPU-intensive task in parallel with other tasks, to improve overall performance
– To run a task that is blocking the main event loop, to avoid disrupting other tasks
– To run a task on a different machine or in a different environment

11. What options exist for running multiple Node.js instances on a single machine?

There are a few options available for running multiple Node.js instances on a single machine. One option is to use a process manager like PM2. Another option is to use a containerization tool like Docker. Finally, you can also use a tool like nvm to manage multiple Node.js versions on a single machine.

12. What is the purpose of cluster module in Node.js?

The cluster module in Node.js is used for creating child processes. This is useful for increasing the performance of an application by taking advantage of multiple cores in a CPU. The cluster module also allows for easy communication between the child processes.

13. What are the main differences between Node.js and other languages like Java or Python?

Node.js is unique among languages because it uses an event-driven, non-blocking I/O model. This makes it ideal for building fast, scalable network applications. Other languages like Java or Python are not as well suited for this type of development.

14. What are the differences between Angular 1 and 2?

Angular 1 is a JavaScript framework while Angular 2 is a TypeScript-based open-source web application framework. Angular 1 uses JavaScript for building web applications while Angular 2 uses TypeScript, which is a superset of JavaScript. Angular 2 is faster than Angular 1 and is more scalable.

15. What are the disadvantages of using Node.js?

While Node.js is a powerful tool, it does have some disadvantages. First, it is not as widely adopted as some other technologies, so there is less of a community to draw on for support. Additionally, Node.js can be less stable than some other options, and it can be challenging to debug.

16. What are some common security issues with Node.js applications?

There are a few common security issues to be aware of when working with Node.js applications. One is the potential for SQL injection attacks if your application is using a SQL database. Another is the possibility of cross-site scripting attacks if your application is not properly sanitizing user input. Finally, there is the risk of denial of service attacks if your application is not properly configured to handle high traffic levels.

17. What is EventEmitter class in Node.js?

EventEmitter is a class that allows you to emit custom events in Node.js. You can create your own events and then trigger them when certain conditions are met. This is a powerful way to build event-driven applications.

18. What are streams in context of Node.js? How are they different from other data structures like arrays or lists?

Streams are a way of handling data that is too large to fit into memory all at once. With streams, you can start processing the data before it is all loaded, which is not possible with an array or list. Streams are also different in that they are not static like an array – data can keep flowing into a stream even after you have started processing it.

19. What are modules in Node.js?

Modules are essentially JavaScript libraries that you can include in your Node.js applications. There are two types of modules: core modules and third-party modules. Core modules are modules that are included with the Node.js installation, and third-party modules are modules that you install from npm.

20. What is the NPM registry?

The NPM registry is a database of all the available packages for Node.js. It is used by the NPM package manager to install, update, and remove packages.