childContextTypes是什么？它有什么用？

childContextTypes用来定义context数据类型，该api从16.3开始已被废弃

使用方式

class MessageList extends React.Component {  getChildContext() {    return {color: "purple"};  }  render() {    return <div>MessageList</div>;  }}MessageList.childContextTypes = {  color: PropTypes.string};