JavaScript - What is "use strict"? What are prototypes, closures? What is the use of arrow functions? What are call, apply, bind functions? What are prototypes, closures, arrow functions? What will be the value of this in different scenarios? What is the difference between let, const, var? Why is the use of "var" discouraged? Is JavaScript multi-threaded or single-threaded? How to use multi-threading with JavaScript? How does asynchronous behavior work in JavaScript? Is JavaScript pass by value or pass by reference? Is JavaScript object-oriented or functional language? What are pure functions? Web development - How to detect performance bottlenecks and improve performance? How are websites loaded step by step? What is the paint step in rendering? React - What are pure components? What is useReducer? What is useLayoutEffect? Write a component that shows a number that auto increments by one every second. Which are different types of testing? Which testing frameworks are generally used with React? Name some functions used in React Testing Library. Programming - Write a program to check if two strings are anagram.