React Interview Questions | Part-1

Hey LinkedIn family! 👋 Exciting times ahead as we embark on a journey into the React universe together! 🚀 Over the next few weeks, I'll be sharing a series of articles that dive deep into the world of React interview questions. Whether you're a seasoned developer brushing up on your skills or a junior developer gearing up for that dream job, these articles are crafted just for you!

we delve into the essentials with 10 foundational React interview questions. From understanding the basics of components to grasping the significance of state and props, we're laying the groundwork for your React proficiency. As we progress through the series, we'll elevate the complexity, tackling more advanced concepts and challenges that you might encounter in technical interviews.

Q1. What is react? what is the role of react in software development?

Answer:

• React is an open-source library.
• React is used for building user interfaces(UI).
• React simplifies the creation of SPA(single page application) by using reusable components.

Q2. What are the Key features of react?

Answer:

there are 7 key features of React:

1. Virtual DOM: React utilizes a virtual representation of the DOM, allowing efficient updates by minimising direct manipulation of the actual DOM, resulting in improved performance.
2. Component-Based Architecture: React structures user interfaces as modular, reusable components, promoting a more maintainable and scalable approach to building applications.
3. Reusability & Composition: React enables the creation of reusable components that can be composed together, fostering a modular and efficient development process.
4. JSX (JavaScript XML): JSX is a syntax extension for JavaScript used in React, allowing developers to write HTML-like code within JavaScript, enhancing readability and maintainability.
5. Declarative Syntax: React have a declarative programming style(JSX), where developers focus on "what" the Ul should look like and React handles the "how" behind the scenes. This simplify the code.
6. Community & Ecosystem: React benefits from a vibrant and extensive community, contributing to a rich ecosystem of libraries, tools, and resources, fostering collaborative development and innovation.
7. React Hooks: Hooks are functions that enable functional components to manage state and lifecycle features, providing a more concise and expressive way to handle component logic.

Q3. What is DOM? what is the difference between HTML and DOM?

Answer:

• DOM stands for Document Object Model. It's like a tree-like structure that represents the elements and structure of a web page.
• Imagine your HTML code as a blueprint, and the DOM as the interactive version of that blueprint that browsers use to manipulate and display content.
• HTML is the language you use to create the structure and content of your webpage, while the DOM is a programming interface that allows you to interact with and manipulate that structure using languages like JavaScript.
• So, HTML is the static blueprint, and DOM is the dynamic, interactive version that browsers use to render and update web pages based on user interactions or scripting.

Q4. What is Virtual DOM? Difference between DOM and Virtual DOM?

Answer:

• DOM represents the structure and content of a website in the form of a tree. With DOM, scripts and webpages can manipulate, modify and identify the components of a website.
• DOM is slow, unlike modern-day websites, which are fluid and reflect modifications almost immediately. DOM was intended for earlier websites, which were static because they were rendered by the server. By contrast, modern-day websites carry out rendering in the browser. Therefore, when using React DOM for modern websites, it’s slow. This is why Virtual DOM exists.
• Virtual DOM is simply a copy of DOM. It has all the components and features of the DOM, but it cannot display the page of a website in a browser.
• When there are changes in a web page, instead of directly updating the real DOM (which can be slow), the changes are first made to the Virtual DOM. Then, the Virtual DOM compares itself to the real DOM to identify the specific updates needed, minimizing the number of changes that must be made in the actual DOM
• the key difference between the Virtual DOM and the real DOM is that the Virtual DOM acts as an intermediary layer, optimizing the update process and improving overall web page speed.

Q5. What are React Components? What are the main uses of it?

Answer:

• React components are like building blocks in a web application that help organize and manage the user interface.
• They are reusable and self-contained pieces of code that represent different parts of a webpage.
• Think of them as Lego pieces that you can use to construct your webpage. Each component has its own functionality and can be easily combined with other components to create a complete and interactive user interface
• For example, you can have a "Button" component for handling user clicks, a "Header" component for displaying the title of your page, and a "Form" component for collecting user input.

Q6. What is SPA(Single Page Application)?

Answer:

• A Single Page Application (SPA) is a type of web application that loads and interacts with content on a single web page, without needing to reload the entire page for each action.
• In traditional websites, when you click on a link or perform an action, the whole page is refreshed, causing delays. SPAs use modern web technologies like JavaScript to dynamically update the content on the same page, providing a smoother and faster user experience.
• Think of it like a virtual book where flipping through pages happens seamlessly, making it feel more like a native application. SPAs often use frameworks like React, Angular, or Vue.js to manage the dynamic content and enhance user interactivity.

Q7. What are the five advantages of React?

• Simple to build Single Page Application(by using components)
• React is cross-platform and open source(free to use)
• Lightweight and very fast (Virtual DOM)
• Large community and Eco system
• Testing is easy

Q8. What are the Disadvantages of React?

• React introduces new concepts like JSX, component-based architecture, and virtual DOM, which can be challenging for junior developers to grasp initially.
• Managing state and props within React components may be confusing for junior developers, especially when dealing with complex applications

Q9. What is the role of JSX in React?

• In React, JSX (JavaScript XML) plays a crucial role by allowing developers to write HTML-like code within JavaScript.
• Imagine you're building a web page with React, and you need to create elements like headers, paragraphs, or buttons. Instead of using plain JavaScript to create these elements, JSX lets you write code that looks similar to HTML
• JSX gets transformed into regular JavaScript by a process called transpiration before it's rendered in the browser, helping React understand and efficiently update the user interface based on the underlying JavaScript logic

Q10. What is the difference between Declarative & Imperative syntax?

• Declarative and imperative syntax refer to two different ways of telling a computer what to do in programming
• Imagine you're instructing a robot to make a peanut butter and jelly sandwich. In imperative syntax, you'd give step-by-step instructions like "take two slices of bread, spread peanut butter on one, jelly on the other, and put them together." It's like micromanaging every detail. Declarative syntax, on the other hand, is like saying, "I want a peanut butter and jelly sandwich." You're telling the robot the result you want without specifying every little step.
• declarative syntax is more focused on what you want to achieve, letting the computer figure out how to do it. It's like giving the computer a goal rather than a detailed plan.

That concludes the first part of our "Mastering React Interviews" series! 🚀 We hope these fundamental questions have provided you with a solid foundation for your React journey. If you've enjoyed this installment, get ready for the next level! 📈 In our upcoming articles, we'll tackle more advanced React concepts that will sharpen your skills and boost your confidence in technical interviews.

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