title: draftjs how to initiate an editor with content
body: <p>Stumbled on this cool text editor, <a href="https://draftjs.org/" rel="noreferrer">draft.js</a> by Facebook.
  I tried to follow the example in Github, but I want to create an editor with content instead of an empty editor.</p>
  <pre><code>var EditorState = Draft.EditorState;
  
  var RichEditor = React.createClass({
     getInitialState(){
        return {editorState: EditorState.createWithContent(&quot;Hello&quot;)}
        //the example use this code to createEmpty editor
       // return ({editorState: EditorState.createEmpty()})
     }
  });
  </code></pre>
  <p>When I run it, it throws an error with the following message &quot;Uncaught TypeError: contentState.getBlockMap is not a function&quot;.</p>