what is memo in reactjs code example

Example 1: react memo

function MyComponent(props) {
  /* render using props */
}
function areEqual(prevProps, nextProps) {
  /*
  return true if passing nextProps to render would return
  the same result as passing prevProps to render,
  otherwise return false
  */
}
export default React.memo(MyComponent, areEqual);

Example 2: import React, { memo } from 'react';

const MyComponent = React.memo(function MyComponent(props) {
  /* only rerenders if props change */
});