title: FormData append - not working
body: <p>Why my code not working ?</p>
  
  <pre><code>var myFormData = new FormData();
  myFormData.append('xxx',1233);
  console.log(myFormData);
  </code></pre>
  
  <p>Why myFormData is empty?</p>
  
  <p><a href="https://repl.it/B8K4" rel="nofollow">https://repl.it/B8K4</a></p>