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This article mainly explains "what are the Node.js interview questions". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what are the Node.js interview questions"?

Guidelines

I suggest you try to answer questions before reading the answers. You may also look for examples of interview questions for your candidates here. I believe these should be diverse as a starting point to help you assess their level.

I think it's not just a correct answer to a question, it also shows how much detail people know. A good answer may lead to a pleasant conversation and may turn nervousness into small talk with colleagues, which is ideal for both sides.

Node.js problem

(1) what is Node.js?

Node.js is a JavaScript runtime environment based on the V8 engine. It allows us to run JavaScript-- outside the browser, usually in a Web server.

(2) what is the use of Node.js?

Considering that the single-threaded nature of Node.js requires us to release the event loop as soon as possible, Node.js performs well with low cyclic complexity when dealing with multiple connections. This makes Node.js an ideal choice for microservices and real-time applications.

(3) what is npm?

Npm stands for Node.js package manager, an acronym for Node.js Package Manager, which consists of a command line interface that we can use to access the online registry of both public and private packages.

(4) how to create a Node.js application from scratch?

We can first create a project folder, and then we navigate to that folder on the command line and run npm init. Finally, we follow the steps to fill in our application information.

(5) what is the function of "npm install"?

It installs the dependencies found in the package.json file.

(6) how to install libraries in Node.js?

Npm install-of-library will install our library and include it as a dependency, and if you add the-- save-dev parameter, it will be included as a devDependency.

(7) how to create a custom script?

We need to go to package.json and add our custom script in the scripts field, and then we can run the script by going to the terminal and running npm run-script-name.

(8) can I use Node.js to create front-end applications?

Browsers can't run Node.js applications, but you can use code such as webpack or Parcel to package the code and turn it into something the browser can run. Nowadays, it is very common to build front-end applications using the Node.js environment. A good example of Node.js at the front end is the Electron framework, which uses both Node.js and chromium to build "native" applications, such as VS Code.

(9) can you mention three popular Node.js frameworks?

Express.js is probably the most popular framework at present, and Koa.js is probably one of the fastest frameworks. Given the use of socket.io, Sails.js is very useful for real-time bilateral communication applications.

(10) what is the use of Express.js?

Express.js makes it very easy to set up routing for our Web application, which makes it a wise choice to create a REST API. It is very flexible and easy to use, where the middleware architecture helps keep the system simple and extensible.

(11) what is Crypto?

Crypto is an internal library of Node.js that provides encryption features, such as encryption and decryption of passwords.

(12) how do we handle local and global scopes in Node.js?

Unlike client-side JavaScript, variables declared in var at maximum scope in Node.js are not global variables, but local variables of the module in which they are located. On the browser, we can access the window object where our global variables are located, and Node.js has an object called global.

(13) does Node.js have access to the file system?

Yes, we can use the fs module to read, write, copy and delete files and folders.

(14) what does non-blocking mean?

This means that a piece of code, such as an asynchronous function, is scheduled to run in the next iteration of the event loop, unblocking the rest of the code and allowing it to continue.

(15) what is an event loop and how does it work?

The event loop makes Node.js asynchronous, which schedules a set of five phases of execution in a loop. The first phase runs the scheduled setTimeout and setInterval callbacks; the second phase runs the IO callbacks scheduled to run on the current iteration; the third phase polls for events that will be executed in the next iteration; the fourth phase runs the setImmediate () callback; and finally, the fifth phase runs all "close" callbacks.

(16) do asynchronous functions run in parallel?

No. When a parallel process runs in its own process or thread, the asynchronous function is executed in the next event loop iteration.

(17) is Node.js multithreaded?

A Node.js process runs in a single thread, but we can use the child_process module to run multiple processes in parallel, or we can use Worker to run multiple threads.

(18) what is a child_process module?

The child_process module enables us to generate and derive child processes. These are separate processes that run in our own CPU, giving us access to system commands.

19) what is the difference between web worker and worker thread?

Web worker is implemented in browsers, and worker thread is implemented in Node.js. They all solve the same problem, which is to provide parallel processing. In fact, Worker Thread API is based on Web Workers.

(20) what are the advantages of using worker thread over child_process?

Child_process runs its own process with its own memory space, while worker thread is a thread in a process that can share memory with the main thread, which helps avoid expensive data serialization back and forth.

(21) what will you use to establish a two-way real-time connection with the client through HTTP?

We can use WebSockets or long polling, and libraries like soket.io and SignalR can simplify the process for us. If WebSockets is not available in the browser, they can even provide long-time polling for the client.

Thank you for your reading, the above is the content of "what are the Node.js interview questions". After the study of this article, I believe you have a deeper understanding of what Node.js interview questions are, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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