Published: August 26, 2024
Reading Time: 10 minutes
With the increasing demand for full-stack web developers, the proficiency in the MERN stack, which consists of MongoDB, Express.js, React.js, and Node.js, has become increasingly valuable. The MERN stack provides a comprehensive toolkit for building modern, scalable web applications, and understanding it is a great advantage to increase your job opportunities.
The MERN stack technical interview questions are quite broad and range from your basic programming expertise to more complicated problem-solving issues. For freshers, MERN stack interview questions might cover topics such as React component lifecycle methods, server-side development with Node.js, or data handling with MongoDB. Familiarity with these questions is essential for overcoming coding challenges during interviews.
The interview stages for MERN stack developers typically involve the following:
Here are the technical interview questions for freshers & Experienced 2024:
A MERN Stack Developer is a software engineer who is responsible for writing server-side web application logic. MERN stack is the combination of MongoDB, Express.js, ReactJS, and NodeJS; which helps in the full-stack development of websites. This stack provides a complete solution from front to backend making it effortless and time-saving.
Higher-order components are functions that take a component and return a new component with additional props or logic. They're used for code reuse, logic abstraction and to make React Component Transformations.
In React, Reconciliation is the process used to update the DOM efficiently. When the state or props of a component change, React compares the new Virtual DOM with the old one and updates only the parts of the Real DOM that have changed.
React.js is a Javascript software library developed by Facebook, is a perfect way to build fast and efficient user interfaces, especially those that are running on a client's computer and can interact without waiting for the server's response.
The main features are:
The MVC architecture has three components: Model, View, and Controller, which work together very closely.
Model: The Model component represents the data and business logic of the application (e.g., MongoDB for data storage).
View: The View represents the user interface of the application (e.g., React components for rendering).
Controller: The Controller component is responsible for receiving users' input and accessing the model components (e.g., routes in Express.js for indicating server-side logic necessary for managing the model).
Streams are objects that allow you to read and write data efficiently. They come in various types including:
In the MERN Stack, Express.js is a powerful framework for creating both server-side web applications and APIs that can serve incoming requests over HTTP, handle all routing requests, and support HTTP client requests from, for example, a client-side React application to a MongoDB database.
Buffers are used to interact with data in raw binary form directly in memory. They provide a method to work with streams of binary data and are needed for tasks such as file manipulation and network communication.
MongoDB is a NoSQL database paradigm designed to be flexible and scalable. It holds data in documents like JSON objects and can offer flexible schemas, indexing, aggregation, and sharding to help manage your data more efficiently, including organizing, retrieving, and managing data.
In a Node.js project, you will manage Node.js dependencies with npm (Node Package Manager) or yarn, which will be used to install, update, and manage the project's dependencies. By creating a package.json file, Node.js will know the project's dependencies. npm or yarn will also create a package-lock.json or yarn.lock file, which makes sure subsequent installs of dependencies will be the same version in different environments.
The event loop in Node.js serves to keep Node.js applications running without interruption. When an asynchronous task is completed, a task gets pushed to the event queue, where the event loop then processes the task before running the task in Node.js's main thread. In this way, Node.js's event loop ensures that JavaScript can run without blocking I/O tasks and without needing to handle asynchronous code in different processes, threads, or environments.
In Express.js, the route handlers, and middleware functions serve distinct purposes:
Route Handlers: Functions that execute when a specific route is requested. They process requests and send responses. Defined using app.METHOD() where METHOD is the HTTP method (e.g., get, post).
Example:
app.get('/', (req, res) => {
res.send('Hello, World!');
});
Middleware Functions: Functions that run before or after route handlers to modify request/response objects or perform tasks like logging and authentication.
Example:
app.use((req, res, next) => {
console.log('Request received');
next(); // Pass control to the next handler
});
Redux is a state management tool that provides a predictable state container for JavaScript applications. Redux is designed to help manage application states in a single store so that state changes are predictable and debuggable within action creators and reducers.
React Router is a library used for handling routing in React applications. It facilitates navigation between different components based on the browser's URL, ensuring that the URL reflects the currently displayed component. This library allows for dynamic component rendering and maintains synchronization between the URL and the view, similar to how web browsers manage URLs.
REPL stands for "Read-Eval-Print Loop." It's an environment within Node.js that provides an interactive mode for the execution of JavaScript code. Below is how the REPL works:
REPL is highly used for testing code snippets and debugging.
A callback is a function passed as an argument to another function once the execution of the other function is completed. Callbacks help handle asynchronous operations like reading files or requests and enable it to be the primary solution for handling such operations, which emphasizes its importance in Node.js. For example, when you read a file, you can provide a callback function, and Node.js will call it once the file is read. It prevents blocking the execution and enables the program to continue running other code while waiting for the task to complete.
JSX is a unique syntax extension for JavaScript, which integrates HTML elements into JavaScript code. JSX assists in making React components easier to write and read. It gets evaluated after it returns an object representation of the virtual DOM.
Middleware in Node.js is a function that deals with requests and responses, among other things. For example, we can utilize middleware to log information, complete authentication, and/or modify the request object. Middleware functions are used with app.use() to fulfill certain aspects of the request-response lifecycle.
RESTful APIs use the HTTP methods (GET, POST, PUT, DELETE) to operate on resources that are addressable via URLs. Statelessness (information is not stored or retained across requests), resource-based interactions (based on HTTP protocol), and the regular use of HTTP methods are principles of RESTful APIs.
In Conclusion, becoming skilled in the MERN Stack is key for a successful web developer in today's job market. The popular MERN Stack topics in 2024 are wide-ranging and include everything from basic to advanced technologies such as MongoDB, Express.js, React.js, and Node.js. By preparing these diverse questions, developers demonstrate their understanding and ability to build scalable applications and solve complex problems.
A) MongoDB, Express.js, React.js, Node.js
B) MySQL, Express.js, React.js, Node.js
C) MongoDB, Ember.js, React.js, Node.js
D) MongoDB, Express.js, Ruby on Rails, Node.js
Answer: A) MongoDB, Express.js, React.js, Node.js
A) npx create-react-app my-app
B) npm install react my-app
C) react new my-app
D) npx react-create-app my-app
Answer: A) npx create-react-app my-app
A) To manage state within functional components
B) To perform side effects in functional components
C) To handle routing within React components
D) To create reusable components
Answer: B) To perform side effects in functional components
A) app.post()
B) app.get()
C) app.put()
D) app.delete()
Answer: B) app.get()
A) Using context API
B) Using hooks
C) Using props
D) Using state
Answer: C) Using props
A MERN Stack Developer is a software engineer who is responsible for writing server-side web application logic. MERN stack is the combination of MongoDB, Express.js, ReactJS, and NodeJS; which helps in the full-stack development of websites. This stack provides a complete solution from front to backend making it effortless and time-saving.
The MERN Stack includes four main technologies: MongoDB (a NoSQL database for storing JSON-like documents), Express.js (a web application framework for Node.js), React.js (a JavaScript library for creating interactive user interfaces), and Node.js (an environment where JavaScript code can run on the server side).
The interview stages for MERN stack developers typically involve three rounds: Initial screening (testing basic knowledge of React and MERN stack), Technical interview (deep technical questions and coding challenges), and Additional Interview if applicable (behavioral interviews, system design discussions, or HR discussion).
Class Components use ES6 class syntax, can have lifecycle methods and manage state internally. Functional Components use functions and hooks (e.g. useState, useEffect) for state management and side effects, are generally easier to read and preferred over classes, and have better performance.
In the MERN Stack, Express.js is a powerful framework for creating both server-side web applications and APIs that can serve incoming requests over HTTP, handle all routing requests, and support HTTP client requests from a client-side React application to a MongoDB database.
Source: NxtWave CCBP
Original URL: https://www.ccbp.in/blog/articles/mern-stack-interview-questions
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