I recently interviewed with Wissen technology for a Frontend Developer role. Here’s my experience and the questions asked in the 1st Round of Interview.

• What is the difference between functional components and class components ?
• Why should developers still learn about class components even though functional components are widely used today ?
• Write a function to flatten a nested array.
• Convert a camelCase string into Capital_Snake_Case. If the input is not a string, return an empty string.
  I/p: "thisIsATest" O/p: "This_Is_A_Test"
• You have a state with an initial value of 10. Decrease it until it reaches 0, then show an alert "Test", and afterwards, start increasing it back to 10.
• O/p Question
  (function immediateA(a) {
  return (function immediateB(b) {
  console.log(a);
  })(1);
  })(0);
• What state management libraries have you worked with ?
• Why do we need state management libraries in the first place ?
• What is props drilling, and how does React Context help solve it ?
• What are the disadvantages of React Context ?
• How would you set up Redux Toolkit in a React application ?
• What React hooks have you worked with ?
• What is the difference between useMemo and useCallback ? Give examples.
• How can you improve the performance of a React application ?
• What is the Virtual DOM in React ?
• How does React compare two Virtual DOMs under the hood ?
• What is the name of the algorithm and process React uses for this comparison ?
• Do you have experience with Server-Side Rendering (SSR) ?
• What rendering model does React use by default ?
• What is the difference between SSR (Server-Side Rendering) and CSR (Client-Side Rendering) ?
• What is hydration in React ?
• What is React Suspense, and how is it useful ?

Verdict - Cleared This Round.