What is used for memoization in React? What will happen if you use useMemo without the second parameter (dependency array)?

React uses the useMemo hook for memoization. It allows you to remember the result of a function calculation and reuse it if dependencies haven't changed, which helps optimize performance.

If you use useMemo without the second parameter (dependency array), memoization won't work as expected: the function will be computed on every component render because React doesn't know what it depends on.

Example of using useMemo:

import React, { useMemo } from 'react';

function Component({ number }) {
  const computedValue = useMemo(() => {
    // heavy computation function
    return number * 2;
  }, [number]); // computation will only repeat when number changes

  return <div>{computedValue}</div>;
}

If you remove [number], the function will be called on every render, which negates the benefits of memoization.