How to set component default props on React component
<p>I use the code below to set default props on a React component but it doesn't work. In the <code>render()</code> method, I can see the output "undefined props" was printed on the browser console. How can I define a default value for the component props?</p>

<pre><code>export default class AddAddressComponent extends Component {

render() {
   let {provinceList,cityList} = this.props
    if(cityList === undefined || provinceList === undefined){
      console.log('undefined props')
    }
    ...
}

AddAddressComponent.contextTypes = {
  router: React.PropTypes.object.isRequired
}

AddAddressComponent.defaultProps = {
  cityList: [],
  provinceList: [],
}

AddAddressComponent.propTypes = {
  userInfo: React.PropTypes.object,
  cityList: PropTypes.array.isRequired,
  provinceList: PropTypes.array.isRequired,
}
</code></pre>