Fresher's Frontend Interview 🎉 | JavaScript | #reactjs (Mock) [Most Asked Questions -2023]

Summary

In this interview, Ritikesh, a web development enthusiast from Hyderabad, demonstrates his foundational knowledge of front-end technologies including HTML, CSS, JavaScript, React, and Git. He shares his educational background and technical skills, such as proficiency in HTML5, JavaScript (ES6 features like arrow functions, promises, etc.), and React concepts like JSX and component lifecycle methods. While Ritikesh has a good understanding of these topics, he also reveals areas for growth, particularly in advanced JavaScript concepts and certain React features. Overall, Ritikesh appears eager to further develop his skills, aiming for a position in a reputed company to contribute and grow.

Takeaways

• 😀 Ritikesh has a solid educational background with an engineering degree, intermediate studies, and schooling in Hyderabad.
• 😀 Ritikesh's core technical skills include HTML, CSS, JavaScript, Git, and React, with an interest in improving and applying these skills in a professional setting.
• 😀 Ritikesh is aiming for a job placement in a reputed company to enhance his technical expertise and contribute to company growth.
• 😀 He is aware of new features in HTML5, such as SVGs, video tags, and semantic elements, compared to older versions of HTML.
• 😀 Ritikesh understands the CSS box model, describing content, padding, margin, and borders in detail.
• 😀 He knows the difference between `let`, `const`, and `var` in JavaScript, and understands variable scoping and initialization.
• 😀 Ritikesh is familiar with basic concepts like callback functions, promises, and the event loop in JavaScript, though there are areas for improvement in explaining these topics.
• 😀 He has a clear understanding of React's component-based structure, JSX (JavaScript + HTML), and the role of React hooks like `useState` and `useEffect` in functional components.
• 😀 Ritikesh knows the importance of controlled and uncontrolled components in React but would benefit from further clarification on this topic.
• 😀 He is familiar with essential Git commands such as `git status`, `git add`, `git commit`, `git push`, and `git pull`, demonstrating basic version control skills.
• 😀 Ritikesh needs further study on advanced JavaScript concepts like the `this` keyword, closures, and deeper understanding of React performance optimization, server-side rendering, and lifecycle methods.

Q & A

What is the difference between HTML and HTML5?

HTML is the basic markup language used to structure web pages. HTML5 is an updated version that introduced new features such as SVG support, video and audio tags, and semantic elements like <header>, <footer>, and <article>.

What is the Box Model in CSS?

The CSS Box Model describes how elements on a webpage are structured. It consists of four parts: content (the actual element), padding (space around the content), border (surrounding the padding), and margin (space outside the border).

What is the difference between margin and padding in CSS?

Margin is the space outside the border, separating the element from other elements, while padding is the space between the content of an element and its border.

What are callback functions in JavaScript and when are they used?

A callback function is a function passed as an argument to another function, which is then invoked after the completion of that function. They are used to handle asynchronous operations, like in event handling or server requests.

What is the purpose of promises in JavaScript?

A promise is used to handle asynchronous operations in JavaScript. It represents a value that may be available now, in the future, or never, and allows handling of success or failure using .then() and .catch() methods.

What are the key differences between 'let', 'const', and 'var' in JavaScript?

'var' has function scope and can be redeclared and updated. 'let' has block scope and can be updated but not redeclared in the same scope. 'const' also has block scope but cannot be updated or redeclared once initialized.

What are lifecycle methods in React?

Lifecycle methods in React are functions that allow you to run code at different stages of a component's life. They include mounting (initialization), updating (state or props changes), and unmounting (cleanup before the component is removed from the DOM).

What is the difference between state and props in React?

State refers to data that changes over time within a component and is managed within the component itself. Props (short for properties) are immutable and are passed from a parent component to a child component to provide it with data.

What is JSX in React?

JSX (JavaScript XML) is a syntax extension for JavaScript that allows HTML-like code to be written in JavaScript. It enables the creation of React elements with HTML syntax but requires a transpiler like Babel to convert it to valid JavaScript.

How does the Virtual DOM in React optimize performance?

The Virtual DOM is a lightweight copy of the real DOM. When a component's state or props change, React compares the Virtual DOM with the real DOM and updates only the changed parts, making the process faster than directly manipulating the real DOM, which can be costly in terms of performance.