title: ReactJS - Checkbox onChange event not firing
body: <p>I'm trying to implement a fields set of checkboxes in React rendered from an object as follows:</p>
  
  <pre><code>constructor() {
  
      this.state.todo = {
          eat: true,
          sleep: false,
          react: true
      }
  
      this.toggleCheckbox = this.toggleCheckbox.bind(this);
  }
  
  toggleCheckbox(e){
  
      console.log(e); // nothing :-/
  }
  
  render() {
  
      return (
      &lt;div&gt;
      { Object.keys(this.state.todo).map((val, i) =&gt; (          
          &lt;div key={i} &gt;
              &lt;input 
                  type="checkbox" 
                  value={val} 
                  onChange={this.toggleCheckbox} 
                  checked={this.state.todo[val]} 
                  /&gt;&lt;label&gt;{val}&lt;/label&gt;
          &lt;/div&gt;
       ))}
       &lt;/div&gt;
      )
  }
  </code></pre>
  
  <p>Everything renders correctly but I am not able change any of the checkboxes. console logging the <code>toggleCheck()</code> event is not being triggered. </p>
  
  <p>Ive tried using <code>onClick</code> vs <code>onChange</code> which has no effect.  </p>