title: Is it possible to apply FormData to an existing form?
body: <p>If I have an existing form, I know I can effectively "convert" it to FormData by passing the form to the FormData constructor like in this example:</p>
  
  <pre><code>var myForm = document.getElementById('myForm');
  
  var myFormData = new FormData(myForm);
  //Now myFormData contains all fields from myForm
  </code></pre>
  
  <p>Is there any way to effectively do the inverse of this operation? I have an existing FormData object, and I want to apply its fields to a form in the DOM. Something like <code>myForm.setFormData()</code> (which I totally made up in) this example:</p>
  
  <pre><code>var myFormData = new FormData();
  myFormData.append(...); //etc...
  
  var myForm = document.getElementById('myForm');
  myForm.setFormData(myFormData);
  //Now myForm contains all fields from myFormData
  </code></pre>
  
  <p>Is there any way to apply FormData to an existing form?</p>