React没有从onClick返回值

Question

export default class CreateMenu extends React.Component {
  constructor(props) {
    super(props);
  }
  goToStage = event => {
    console.log(event.target.value);
    if (event.target.value < this.props.stage) {
      console.log('true')
    }
  };
  render() {
    return (
      <div className="campaign-pagination">
        <ul>
            <li>
            <span value={0} onClick={this.goToStage} className={this.props.menu.home} title="Info">
              <AlignLeft />
              <span className="navigation-text">1. Info</span>
            </span>
          </li>

尝试从值设置为0的范围访问“ event.target.value”。出于某种原因，它仅返回null。