【propTypes】
React.PropTypes is deprecated as of React v15.5. Please use the prop-types library instead.
You can define default values for your props by assigning to the special defaultPropsproperty:
参考：https://facebook.github.io/react/docs/typechecking-with-proptypes.html
原文：http://www.cnblogs.com/tekkaman/p/6785703.html