title: React.js - How do I set a checked/selected radio button and track the onChange?
body: <p>I have a radio group for the days of the week in a component. If the user already has a day associated with their account, I want that to be the selected/checked radio button. So if they've previously saved "monday", I'll be getting that from the parent and storing it in the state, and want it to be selected when the page renders. </p>
  
  <p>I was trying to set it up similar to how it's done in the React Forms for select, but it doesn't seem to work for Fieldset. Any ideas?</p>
  
  <pre><code>constructor(props) {
    super(props);
    this.state = {
      reportWeekday: "monday"
    }
  }
  
    handleWeekdayChange(event){
      this.setState({reportWeekday: event.target.value});
      console.log(event.target.value);
    }
  
    &lt;fieldset className="schedule-weekday" value={this.state.reportWeekday} onChange={this.handleWeekdayChange}&gt;
      &lt;label for="sunday"&gt;&lt;input type="radio" name="schedule-weekly-option" value="sunday" id="sunday" /&gt;Sunday&lt;/label&gt;
      &lt;label for="monday"&gt;&lt;input type="radio" name="schedule-weekly-option" value="monday" id="monday" /&gt;Monday&lt;/label&gt;
      &lt;label for="tuesday"&gt;&lt;input type="radio" name="schedule-weekly-option" value="tuesday" id="tuesday" /&gt;Tuesday&lt;/label&gt;
      &lt;label for="wednesday"&gt;&lt;input type="radio" name="schedule-weekly-option" value="wednesday" id="wednesday" /&gt;Wednesday&lt;/label&gt;
      &lt;label for="thursday"&gt;&lt;input type="radio" name="schedule-weekly-option" value="thursday" id="thursday" /&gt;Thursday&lt;/label&gt;
      &lt;label for="friday"&gt;&lt;input type="radio" name="schedule-weekly-option" value="friday" id="friday" /&gt;Friday&lt;/label&gt;
      &lt;label for="saturday"&gt;&lt;input type="radio" name="schedule-weekly-option" value="saturday" id="saturday" /&gt;Saturday&lt;/label&gt;
    &lt;/fieldset&gt;
  </code></pre>