setting state of component in reactjs

Calling the file

var renderTabsContent = function(content){
 	
	if(typeof content === 'object') { 
		
		return(
		    <span dangerouslySetInnerHTML={{__html: content.text }} />						
			  
		);
	} else if (typeof content === 'string'){

		var text = content; 
		var language = editorContent.language;
		var code = editorContent.content;

		return(<div className="tab-inner-content ">  					
					<CodeEditor value={code} mode={language} height="400px" width="350px" />
				</div>
		);	
	}

}

gistfile1.txt

var CodeEditor = React.createClass({

getInitialState: function() {
   return {language: 'javascript'};
 },

changeLanguage: function() {
  var language = document.getElementById('lang-select');

  language = language.options[language.selectedIndex].value;


  this.setState({
    language: language

  });
},

render: function() {

  return(
      <div id="code-editor">
                <div className="col-xs-6">
                          <h5>Change Language </h5>
                          <select id="lang-select" className="form-control" onChange={this.changeLanguage}>
                                    <option value="javascript" >Javascript</option>
                                    <option value="java">Java</option>
                                    <option value="php">PHP</option>
                                    <option value="python">Python</option>
                                    <option value="xml">XML</option>
                                    <option value="ruby">Ruby</option>
                                    <option value="sass">SASS</option>
                                    <option value="markdown">Mark Down</option>
                                    <option value="mysql">Mysql</option>
                                    <option value="json">JSON</option>
                                    <option value="html">HTML</option>
                                    <option value="handlebars">Handlebars</option>
                                    <option value="golang">Go</option>
                                    <option value="csharp">C#</option>
                                    <option value="coffee">Coffee Script</option>
                                    <option value="css">CSS</option>
                            </select>
                    </div>
              <AceEditor mode={this.state.language} value={this.props.value} theme="monokai" height="400px" width="900px" id="react-editor" />
                    
          </div>

    );

  }

});