Wissen Technology | Frontend Developer | August 2025 | 3.5 YOE
Summary
I successfully cleared the first round interview for a Frontend Developer role at Wissen Technology, which focused heavily on React concepts and JavaScript fundamentals.
Full Experience
I recently interviewed with Wissen Technology for a Frontend Developer role, and this post details my experience and the questions asked in the 1st Round of Interview. The interview covered a wide range of topics, from fundamental JavaScript concepts to advanced React features, state management, and performance optimization. I found the questions to be comprehensive, testing both my theoretical knowledge and practical coding skills. I am happy to report that I cleared this round.
Interview Questions (22)
Difference between Functional and Class Components
Explain the key differences between functional components and class components in React.
Importance of Class Components
Discuss why developers should still learn about class components despite the widespread adoption of functional components with hooks.
Flatten Nested Array
Write a JavaScript function to flatten a nested array (e.g., [1, [2, [3, 4]], 5] becomes [1, 2, 3, 4, 5]).
camelCase to Capital_Snake_Case Conversion
Write a function that converts a camelCase string into Capital_Snake_Case. If the input is not a string, it should return an empty string. For example, thisIsATest should become This_Is_A_Test.
State Manipulation with Alert
Describe or implement a mechanism where a state variable, initialized to 10, decreases to 0. Upon reaching 0, an alert displaying 'Test' should be shown, and then the state should start increasing back to 10.
JavaScript IIFE Output Question
Determine the output of the following JavaScript Immediately Invoked Function Expression (IIFE) code snippet:
(function immediateA(a) {
return (function immediateB(b) {
console.log(a);
})(1);
})(0);Experience with State Management Libraries
List and discuss state management libraries you have experience working with in frontend development.
Need for State Management Libraries
Explain the fundamental reasons why state management libraries are necessary in complex frontend applications.
Props Drilling and React Context
Define 'props drilling' in React and explain how the React Context API helps to mitigate or solve this problem.
Disadvantages of React Context
Discuss the potential disadvantages or drawbacks of using React Context.
Setting up Redux Toolkit
Describe the steps and considerations for setting up Redux Toolkit in a React application.
Experience with React Hooks
List and briefly explain the React hooks you have experience working with.
Difference between useMemo and useCallback
Explain the difference between useMemo and useCallback hooks in React, providing examples for their use cases.
React Application Performance Optimization
Discuss various strategies and techniques to improve the performance of a React application.
What is React Virtual DOM?
Explain what the Virtual DOM is in the context of React and its purpose.
React Virtual DOM Comparison
Describe the process React uses internally to compare two Virtual DOMs when state or props change.
React Reconciliation Algorithm
Identify the name of the algorithm and the process React uses for comparing Virtual DOMs and updating the real DOM.
Experience with Server-Side Rendering (SSR)
Discuss your experience with Server-Side Rendering (SSR) in web development, particularly with React.
Default React Rendering Model
Identify the default rendering model utilized by React applications.
SSR vs. CSR Comparison
Explain the key differences between Server-Side Rendering (SSR) and Client-Side Rendering (CSR) in web development.
What is React Hydration?
Define 'hydration' in the context of React and server-side rendering.
React Suspense and its Utility
Explain what React Suspense is and describe its utility and benefits in a React application.