title: How to get the value of the date input in ReactJS?
body: <p>I have a Signup form that takes a date as input.</p>
  
  <p>The code of my date input is:</p>
  
  <pre><code>birthDate: new Date(),
  
  this.handleSubmit = this.handleSubmit.bind(this);
  this.handledChange = this.handledChange.bind(this);
  
  
  handledChange(date) {
    this.setState({
      birthDate: date
    });
  }
  
  &lt;ControlLabel&gt;Date de naissance&lt;/ControlLabel&gt;
    &lt;FormGroup controlId="birthDate" bsSize="large"&gt;
      &lt;FormControl
        autoFocus
        type="date"
        value={this.state.birthDate}
        onChange={this.handledChange}
      /&gt;
    &lt;/FormGroup&gt;
  </code></pre>
  
  <p>When I submit it, the input date is <code>undefined</code> on the console.</p>
  
  <p>I want it in the format : <code>YYYY-MM-DD</code></p>
  
  <p>How can I fix that please?</p>