12 Node.js Developer & Programmer interview questions and answers

This is a popular programming approach, especially in JavaScript. In these types of programs, one event triggers another. To benefit you and your organization, see how they describe event-based programming in a Node.js application. They should mention a callback function as well as talk about the productivity of the language.

You want to ask this to see if the developer knows this programming language should be the one for your company. A developer who knows what they're talking about will mention some technical terms, like the system's non-blocking I/O operations. Still, they will also describe an event-based model with shorter response times and concurrent processing. They may also mention current platforms where the tech is used, including Paypal and Microsoft.

Node comes with the REPL environment when it's installed, and the system interacts with outputs of command lines or expressions. This environment is useful in writing and debugging code. It could be useful in helping your program assess the functionality and debugging the code. 

The reason you'll want to ask this in your interview is to show how succinct the coder is with their JavaScript code. Callback functions usually amount to functions within functions, but promises can make coding more succinct and easier to understand and potentially debug later. They may also use the term callback hell to refer to why you should use promises instead of callbacks.

Depending on the developer, you may receive a detailed response on why the V8 engine is necessary. In addition, a developer may mention other features such as memory structure, Garbage collector, and memory leaks. If they're a brand new developer, they may not have a developed answer to this question, but questions about single-thread in Node.js will help further assess their ability. 

Like other questions, this should tell you if your coder knows their stuff. Node.js is a JavaScript application designed as an experiment in asynchronous processing over a single thread. This Node.js interview question will tell you if they truly know how to implement the code. You can take this section a step further and ask them to draw a diagram asking how the language handles concurrency. 

Node.js is built up of event loops. Event loops are made up of different phases with specific events, and in between iterations, it checks for async I/O and shuts down cleanly if there aren't any. So a coder should understand how this functions and walk you through a loop if you asked them to do so.

This question can help you determine how experienced a Node.js programmer is. This is the heart of the app, where various metadata lives, including modules, libraries, and packages. A junior developer should tell you that the package.json file will make the program reproducible. They may also mention two fields within the file: name and deals. 

The question touches on some other technologies such as C# and Java. It covers some obsolete types of Node.js such as relational databases. Overall, this question also addresses responsiveness under intense CPU computation. This should give your talent a chance to express what app or web applications would result in the questionable effectiveness of Node.js. A couple of key points to look out for are unstable API and asynchronous function.

Objects in Node.js are capable of emitting events. For example, during a Node.js interview, a programmer will mention that they generate events by attaching named events caused by the object using the eventEmitter.on () function, which will result in synchronous parts. 

This is super important to any project that requires streaming data like live video. Node.js uses four types of streams, and your developer should be able to differentiate when and where each type should be used. The four types of streams are readable, writable, duplex streams, and transform.

Child processes are a way to handle an event queue so large it runs the risk of overloading the CPU. Since this is a problem that your developer might face in working with JavaScript, they should be familiar with how it functions.