set initial react component state in constructor or componentWillMount? : <p>In react components is it preferred to set the initial state in the constructor() or componentWillMount()?</p>

<pre><code>export default class MyComponent extends React.Component{
  constructor(props){
    super(props);
    this.setState({key: value});
  }
}
</code></pre>

<p>or</p>

<pre><code>export default class MyComponent extends React.Component{
  componentWillMount(props){
    this.setState({key: value});
  }
}
</code></pre>
