Node.js Interview Questions And Answers
Node.js Interview Questions For Freshers
Let us start by answering a few node.js interview questions for freshers. You can expect these basic questions as a fresh college graduate or a professional without substantial experience with node.js.
First-class functions are the functions that can be used by developers like any other variable. Along with JavaScript, there are many other programming languages that follow this approach, such as Haskell, Scala, and more. This allows a function to be passed as a param to a different function(callback) or return a different function(higher-order function). Filer() and map() are the two higher-order functions used properly by node.js developers.
The packages in a node.js project can be managed with the help of several package installers and their corresponding configuration files. Most developers work with yarn or NPM. They also use package -lock.json and package.json to maintain library versions being installed in a node.js project. This eliminates any issues that may arise while porting an application to a different environment.
Node.js provides developers with the simplicity that most technologies lack due to its non-blocking I/O as well as the event-based model. These features result in shorter response times and concurrent processing, preventing developers from using thread management.
Moreover, node.js runs on the valuable Chrome v8 engine powered by Google. Written in C++, the engine adds to the performance of your applications and ensures consistent improvement. Node.js also makes web app development faster as it uses JavaScript for both front-end and back-end development.
Here are the major steps that Control Flow follows to control the function calls in node.js:
- Controlling the execution order
- Collecting data
- Limiting concurrency
- Calling the next step in the program
The biggest benefit of working with promises instead of callbacks in node.js is that they give you an object to determine the action you should take after the completion of the async task. This allows you to work with a more manageable code and keeps you away from the complications of callbacks.
In node.js development, a fork refers to a component used for spawning child processes. It allows developers to create a new v8 engine instance for running multiple workers to ensure seamless code execution.
Node.js was developed as an experiment in asynchronous processing. It was a massively successful attempt in making async processing work on a single thread instead of sticking to the existing thread-based scaling implementation through multiple frameworks.
Here are the two types of API functions available in node.js:
- Synchronous and blocking functions - These functions are attributed to operations that influence processing running in the main loop.
- Asynchronous and non-blocking functions - These functions are attributed to I/O operations which can be forked out of the main loop.
Both process.nextTick() and setImmediate() are used by node.js developers for switching to an asynchronous operation mode through listener functions. However, the process.nextTick() sets the callback for execution, while setImmediate() pushes it back into the queue for execution.
This is how the event loop runs:
Timers -> pending callbacks -> idle, prepare -> connections (data, poll, etc.) -> check -> close callbacks
Here, process.nextTick() adds the callback function to the beginning of the following event queue and setImmediate() to keep the function in the check phase of the following event queue.
Advanced Node.js Interview Questions
Let us now have a look at a few important node.js interview questions for experienced developers and IT professionals applying for senior positions:
In node.js, EventEmitter is a class including all objects capable of emitting events. Events can be emitted by attaching names of events emitted by an object with the help of the eventEmitter.on() function. Whenever this object throws an event, the functions attached therein are involved in sync.
It is well-known that node.js apps run on a single processor, implying that they do not take advantage of the multiple-core system by default. With the cluster mode, you can trigger multiple node.js processes to have multiple instances of the event loop.
When you start using cluster in a node.js application behind the scene, it leads to the creation of different node.js processes along with a parent process known as the cluster manager. The cluster manager is responsible for overlooking the health of every instance of your node.js application.
In node.js, the thread pool is handled by the libuv library. Libuv refers to a multi-language C library that gives you holistic support for asynchronous I/O operations like networking, concurrency, and file systems.
In the case of clusters, there is one process on every CPU with a corresponding IPC for communication. If you wish to have multiple servers accepting HTTP requests through a single port, clusters can prove to be useful under such circumstances. Therefore, clusters result in the spawning of the processes in every CPU, each of them having standalone memory and node instance.
On the other hand, in the case of worker threads, there is one process with different threads. Every thread here has one node instance with most APIs being accessible. Here, every thread shares memory with other threads, making it an ideal option for performing CPU-intensive tasks like data processing and accessing file systems.
Frequently Asked Questions
Why are organizations all over the world looking for skilled Node.js developers?
Organizations worldwide are looking for Node.js developers because the technology has stayed relevant over the years. It allows companies to build robust and scalable web applications capable of running across multiple platforms. It also facilitates freer data exchange than most technologies, making app development faster, easier, and more flexible.
Why do developers use Node.js for backend development?
Developers use Node.js for backend development due to its fast and lightweight nature. The technology is capable of employing the JavaScript code on both the front-end and backend, leading to new development opportunities.
What is a Node.js developer's salary in India?
In India, the salary of a skilled Node.js developer can be anywhere between ₹1.2 lacs and ₹12 lacs. This package can increase with more experience, expertise, and certifications.
Will Node.js stand the test of time?
Looking at the rate at which Node.js is being used in building powerful web applications across the globe, it is safe to say that it will stand the test of time. Landing a Node.js developer job today will secure your future and expose you to a plethora of lucrative opportunities.
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