Node JS Interview Questions


With the advancement of technology, many new start-ups are trying to invade in the IT industry. Node.js is also one of them who makes its position in the top ranks. It is a run-time environment of JavaScript that runs the server-side JavaScript codes. In short, we can say that Node.js extends the range of JavaScript applications from client side to server side. The main focus of Node.js is to design real-time applications with the help of its asynchronous behavior and event-driven approach. Well, I can't define all about Node.js in the introduction.

  • What is let const and var ?
    Node Js

    Posted By: Anthony

  • What is difference between return and callback?
    Node Js

    Posted By: Clovis

  • What do you understand by middleware?
    Node Js

    Posted By: Harold

  • How to connect NodeJS with mongodb?
    Node Js

    Posted By: Bryant

  • How does Promise and Queue work?
    Node Js

    Posted By: Christian

  • Describe Node.js event loop and event driver architecture?
    Node Js

    Posted By: Peter

  • How are Promises better than callbacks ?
    Node Js

    Posted By: sohan

  • What is JIT and how is it related to Node?
    Node Js

    Posted By: Jim

  • What is callback hell?
    Node Js

    Posted By: Alan

  • Why do you use forever with Node.js?
    Node Js

    Posted By: Ellis

  • Why Node.js is based on single threaded architecture?
    Node Js

    Posted By: Hollis

  • What is the difference between Node.js and Ajax?
    Node Js

    Posted By: Jeromefoova

  • What is REPL in Node.js?
    Node Js

    Posted By: Arden

  • What is a Buffer in Node.js?
    Node Js

    Posted By: Gustave

  • What are Global object in Node.js?
    Node Js

    Posted By: paras

  • What is the use of Zlib in Node.js?
    Node Js

    Posted By: PatrickLon

  • What is NPM? How to uninstall a dependency using npm?
    Node Js

    Posted By: Willie

  • What is Piping in Node?
    Node Js

    Posted By: Justus

  • Which module is used for buffer based operations in NodeJs?
    Node Js

    Posted By: KissQuada

  • Explain Chaining in NodeJs?
    Node Js

    Posted By: Wellington

Let's get down and look at the Node.js online interview questions, pros and cons to know more about it.

Which to choose and when?

Node.js is a JAvaScript framework PHP is a server-side scripting language Node.js is powered by the Google V8 JavaScript engine.PHP is powered by Zend engines.
It is the server-side runtime environment of JavaScript.PHP has a ready to install feature to use it on the server side
Node.js is asynchronous PHP is synchronous.Node.js is not much complex to use but more than PHP due to more lines of coding.PHP is much simpler to use in contrast with NodeJS
Node.js is fast and lightweight in comparison to PHPPHP is slower than Node.js
It has a Node Package Manager to use.It mainly uses Composer Package manager.


  • Easy scalability: The utmost advantage is that it provides developers with a simple way to scale the applications in horizontal as well as in the vertical directional. You can easily scale horizontal manner by adding an extra node to the system and vertical manner by adding the optional resources to the single nodes. So, it is highly scalable and therefore developers find it better than the other servers
  • Fast and event-based: Synchronization is very fast when you are using a common language on both the sides (server- side and client-side) which is useful for event-based applications. It is all due to its asynchronous, non-blocking, single-threaded nature that many companies migrated their previous technologies to develop Node.js applications.
  • Real-time applications: NodeJS is quite famous for the event-driven approach, so it is widely used for real-time applications. It is quite popular for online gaming, video conferences, chats or any solution that requires constantly updated data. So, you can see the examples speak by itself.
  • Large community support: One of the most astonishing features of the Node.js is that it is blessed with a large community. The developers are active all the time who always ready to contribute toward the development and growth of the Node.js. Indeed, developers are fully supported by the JavaScript proved easy and ready-made solutions and GitHub codes. It may be possible that the developers will influence many more developers in the nearby future.
  • Rich ecosystem: The default package manager of the Node.js is NPM which plays a vital role in the advancement of the technology. NPM works as a marketplace for open source JavaScript tools. There are almost 350,000 tools are available in the NPM registry by now. Not only this, more than 10,000 new ones being published every week. So, you can see at the time of you are reading this a lot of tools has already been added.

Caching:The facility of caching is important for increasing speed and performance. Node.js also supports this feature to cache the single modules. After the first request for a module, it gets cached in memory and whenever the developer needs to re-execute it, it reloads from the cache memory.Node.js as a blessing:Undoubtedly, Node.js proves to be a blessing for the developers and has become a sure shot savior for heavy load web applications. For instance, chat applications run on high traffic and lightweight model and this criterion followed by Node.js only.


  • Application Programming Interface (API) is Not Stable

    It is one of the key problems of Node.js is that its API is not stable. Most of the developers find that in every interval of time API keeps on changing. From time to time, a new API shown which have a lot of backward-incompatible changes. Therefore, developers have to make changes in the accessible code bases so that they can match the compatibility with the latest version.

  • Asynchronous Programming Model

    Another drawback of the asynchronous programming is that the codes tend to become clumsy It is necessary to adopt the asynchronous programming model to make the application more scalable. But many developers find it very difficult in comparison with the linear blocking I/O programming.

  • Incapable of handling CPU-intensive apps

    As Node.js is an event-based and a single threaded environment, it is not efficient to handle CPU- intensive apps. Some of the requests that Node.js is not capable of handling are generating audio, video, or editing graphics.