what was changed

React.Component.js

class App extends React.Component {

  shouldComponentUpdate(nextProps, nextState) {
    const nextPropsKeys = Object.keys(nextProps);
    const nextStateKeys = Object.keys(nextState);

    for (let i = 0; i < nextPropsKeys.length; i++) {
      const key = nextPropsKeys[i];

      if (nextProps[key] !== this.props[key]) {
        console.log(`App: props.${key} has changed`);
      }
    }

    
    for (let i = 0; i < nextStateKeys.length; i++) {
      const key = nextPropsKeys[i];

      if (nextState[key] !== this.state[key]) {
        console.log(`App: state.${key} has changed`);
      }
    }

    return true;
  }
}