Wissen Technology Interviews

Explain the key differences between functional components and class components in React.

Discuss why developers should still learn about class components despite the widespread adoption of functional components with hooks.

Write a JavaScript function to flatten a nested array (e.g., [1, [2, [3, 4]], 5] becomes [1, 2, 3, 4, 5]).

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.

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.

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);

List and discuss state management libraries you have experience working with in frontend development.

Explain the fundamental reasons why state management libraries are necessary in complex frontend applications.

Define 'props drilling' in React and explain how the React Context API helps to mitigate or solve this problem.

Discuss the potential disadvantages or drawbacks of using React Context.

Describe the steps and considerations for setting up Redux Toolkit in a React application.

List and briefly explain the React hooks you have experience working with.

Explain the difference between useMemo and useCallback hooks in React, providing examples for their use cases.

Discuss various strategies and techniques to improve the performance of a React application.

Explain what the Virtual DOM is in the context of React and its purpose.

Describe the process React uses internally to compare two Virtual DOMs when state or props change.

Identify the name of the algorithm and the process React uses for comparing Virtual DOMs and updating the real DOM.

Discuss your experience with Server-Side Rendering (SSR) in web development, particularly with React.

Identify the default rendering model utilized by React applications.

Explain the key differences between Server-Side Rendering (SSR) and Client-Side Rendering (CSR) in web development.

Define 'hydration' in the context of React and server-side rendering.

Explain what React Suspense is and describe its utility and benefits in a React application.

The first DSA coding question in the OA round was finding the pivot index.

An SQL question in the OA round was finding the employee with the second highest salary.