I want to get the text content of the react element. In the example below, I want get: `hello 1`

```
var node = <myComponent id={1} />

class myComponent extends React.Component {

render() {
  return {
    <span> hello {this.props.id} </span>
  }
}

```

I tried to use `node.text` or `ReactDOM.findDOMNode(node).textContent`, but it doesn't work. Can I get some help?

Thanks!