title: React-DatePicker - Format not Defined
body: <p>I Tried to Implement React Datepicker Function number 32 <a href="https://reactdatepicker.com/" rel="nofollow noreferrer">https://reactdatepicker.com/</a>.</p>
  <p>Here is the Documentation Code they provided</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>handleChange (date) {
    this.setState({startDate: date})
    this.toggleCalendar()
  }
  
  toggleCalendar (e) {
    e &amp;&amp; e.preventDefault()
    this.setState({isOpen: !this.state.isOpen})
  }
  
  &lt;div&gt;
      &lt;button
          className="example-custom-input"
          onClick={this.toggleCalendar}
          {format(this.state.startDate, "dd-MM-yyyy")}
      &lt;/button&gt;
      {
          this.state.isOpen &amp;&amp; (
              &lt;DatePicker
                  selected={this.state.startDate}
                  onChange={this.handleChange}
                  withPortal
                  inline /&gt;
          )
      }
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  <p>What My Problem is, &quot;Format is not defined&quot; error gets throwing.
  what mistake i made here?<br />
  Please Help.</p>