Node.js is a popular JavaScript runtime that is used to create lightning-fast network applications. It is incredibly efficient and allows developers to quickly design apps with little effort. Examine the top Node.js interview questions and answers that are most likely to be asked in an interview.
What Exactly Is Node.js?
Node.js is a server-side programming language that is used to create scalable apps. It is a web application framework based on the JavaScript Engine in Google Chrome. It runs unchanged in the Node.js runtime on Mac OS, Windows, and Linux. This runtime allows you to execute JavaScript code on any computer other than a browser.
What Exactly Is The Node.js Process Model?
Node.js runs in a single process, and the application code executes in a single thread, using fewer resources than competing platforms.
Any user queries to your web application will be processed by a single thread, and all I/O work or long-running jobs will be executed asynchronously for each request. As a result, this single thread is not required to wait for the request to be completed and is free to process the next request. When the asynchronous I/O task is finished, the request is processed further and the answer is sent.
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Explain How Node.js Works
When a Node.js application is invoked, it generates a single thread. When Node.js gets a request, it first processes it before proceeding to the next request.
Node.js handles several requests in parallel asynchronously by leveraging the event loop and callback methods. An Event Loop is a feature that handles and processes all external events and simply turns them to callback functions. It calls all of the event handlers at the appropriate moment. As a result, a lot of work is done on the back end when processing a single request, so that the next incoming request does not have to wait if the processing isn’t finished.
When Node.js processes a request, it adds a callback function to it and sends it to the backend. When the response is ready, an event is triggered, which causes the corresponding callback function to transmit the response.
In Your Node.js Project, How Do You Handle Packages?
A variety of package installers and their configuration files can handle it. They generally make use of npm or yarn. Both offer almost all javascript libraries with expanded functionality for manipulating environment-specific parameters. We utilize package.json and package-lock.json to manage versions of libraries installed in a project so that migrating that app to a new environment is not a problem.
Why Is Node.js Just One Threaded?
To facilitate async processing, Node.js employs a single threaded paradigm. An application that uses async processing performs faster and is more scalable under web loads. As a result, Node.js employs a single-threaded model approach rather than the more common thread-based solution.
What Do You Mean by Node.js Callback Hell?
Callback hell is an issue that arises when a JavaScript developer attempts to perform many asynchronous actions one after the other. When some external action must be completed before processing a result, a function is said to be asynchronous. It is named asynchronous because the time it takes for a result to become accessible is unexpected. To handle problems and process the output, these methods need a callback function.
What Are The Advantages And Disadvantages of Node.js?
Pros:
- If your program does not need any CPU-intensive calculation, you may write it entirely in Javascript, even down to the database level if you use a JSON storage object database like MongoDB.
- Crawlers get a fully rendered HTML response, which is considerably more SEO friendly than a single page application or a Node.js-based websockets app.
Cons:
- Any intense CPU calculation will cause the node to become unavailable.
- JavaScript responsiveness, hence a threaded platform is preferable.
What Is a Node.js Event Loop And How Does It Work?
In Node.js, an event loop manages all asynchronous callbacks in an application. It is one of the most significant components of Node.js and the cause for non-blocking I/O in Node.js. Because Node.js is an event-driven language, you can simply connect a listener to an event, and when the event happens, the listener will perform the callback. When functions such as setTimeout, http.get, and fs.readFile are invoked, Node.js executes the event loop and then continues with the code without waiting for the result. When the operation is complete, Node.js gets the output and performs the callback function. This is why, in a loop, all callback functions are queued. They are carried out one by one after receiving the answer.