Verifies that children has only one child (a React element) and returns it. Otherwise this method throws an error.

那么现在为什么仅使用props.children会有帮助？

主要原因是它抛出一个错误,因此停止整个开发环境,所以你不能跳过它.

这是一个方便的工具,它创建了一个特定的层来执行这个只有一个孩子的特定规则.

当然你可以使用propTypes,但它们只会在你可能会错过的控制台中发出警告.

React.Children.only的一个用例可以是强制执行特定的声明性接口,该接口应包含一个逻辑子组件：

class GraphEditorEditor extends React.Component {
  componentDidMount() {
    this.props.editor.makeEditable();
    // and all other editor specific logic
  }

  render() {
    return null;
  }
}

class GraphEditorPreview extends React.Component {
  componentDidMount() {
    this.props.editor.makePreviewable();
    // and all other preview specific logic
  }

  render() {
    return null;
  }
}

class GraphEditor extends React.Component {
  static Editor = GraphEditorEditor;
  static Preview = GraphEditorPreview;
  wrapperRef = React.createRef();

  state = {
    editorInitialized: false
  }

  componentDidMount() {
    // instantiate base graph to work with in logical children components
    this.editor = SomeService.createEditorInstance(this.props.config);
    this.editor.insertSelfInto(this.wrapperRef.current);

    this.setState({ editorInitialized: true });
  }

  render() {
    return (
      <div ref={this.wrapperRef}>
        {this.editorInitialized ?
          React.Children.only(
            React.cloneElement(
              this.props.children,{ editor: this.editor }
            )
          ) : null
        }
      </div>
    );
  }
}

可以像这样使用：

class ParentContainer extends React.Component {
  render() {
    return (
      <GraphEditor config={{some: "config"}}>
        <GraphEditor.Editor> //<-- EDITOR mode
      </GraphEditor>
    )
  }
}

// OR

class ParentContainer extends React.Component {
  render() {
    return (
      <GraphEditor config={{some: "config"}}>
        <GraphEditor.Preview> //<-- Preview mode
      </GraphEditor>
    )
  }
}

希望这个对你有帮助.