title: FormData Returns empty data on form submission in react
body: <p>I am trying to get the form data key-value pair object when the form is submitted, using the <code>new FormData()</code> constructor. But it always returns empty data.</p>
  
  <p>I have already tried <code>event.persist()</code> to avoid react event pooling, but nothing worked</p>
  
  <pre><code>
  export default class Test extends React.Component {
    constructor(props) {
      super(props);
      this.handleSubmit = this.handleSubmit.bind(this);
    }
  
    handleSubmit(event) {
      event.preventDefault();
      const target = event.target;
      const data = new FormData(target);
      console.log(data)
    }
  
    render() {
      return (
        &lt;form onSubmit={this.handleSubmit}&gt;
          &lt;label htmlFor="username"&gt;Enter username&lt;/label&gt;
          &lt;input id="username" name="username" type="text" /&gt;
  
          &lt;button&gt;Send data!&lt;/button&gt;
        &lt;/form&gt;
      );
    }
  }
  </code></pre>
  
  <p>I am expecting an object that contains my form data in the following format</p>
  
  <p><code>{ "username": "Value" }</code></p>