Should I wrap all my components with React. Memo () if it is not expecting any props?

No, you should not wrap all components with React.memo(), especially those that do not receive any props. React.memo is a higher-order component primarily used for performance optimization. It avoids unnecessary re-renders by performing a shallow comparison of the component's props. When the component's props do not change, React.memo prevents re-renders, thereby improving application performance.

However, if a component does not receive any props or does not depend on external props, using React.memo is unnecessary because such components are unlikely to undergo unnecessary re-renders due to changes in parent components. For such components, React is smart enough to manage internal state changes and component updates on its own.

For example, consider a component that displays the current time, which updates the time internally using its own state and setInterval, and does not receive any external props:

javascript
class Clock extends React.Component {
  state = { currentTime: new Date().toLocaleTimeString() };

  componentDidMount() {
    this.timerID = setInterval(
      () => this.setState({ currentTime: new Date().toLocaleTimeString() }),
      1000
    );
  }

  componentWillUnmount() {
    clearInterval(this.timerID);
  }

  render() {
    return <div>当前时间：{this.state.currentTime}</div>;
  }
}

In this example, wrapping the Clock component with React.memo is unnecessary because its output is entirely controlled by internal state and is unrelated to external props. Therefore, using React.memo only adds extra performance overhead without providing any actual performance benefits.

In summary, when deciding whether to use React.memo, consider the following points:

1. Does the component receive any external props?
2. Are the props likely to remain unchanged across different render cycles?
3. Is the component's rendering expensive enough to warrant optimization?

Only when the answers are affirmative is using React.memo meaningful.