在constructor把props传的值附一个初始值

constructor(props) {
    super(props);
    const data = props.data || [];
    this.state = {
      data,
    };
  }

getDerivedStateFromProps中监听props的变化

static getDerivedStateFromProps (props, state) {
    const data = props.data || state.data;
    if (data !== state.data) {
      return {
        data,
      };
    }
    return null;
  }