title: FormData append JSON
body: <p>How can I create the following result using FormData</p>
  
  <pre><code>------WebKitFormBoundaryOmz20xyMCkE27rN7
  Content-Disposition: form-data; name="data";
  Content-Type: application/json
  
  {
    "description": "description"
  }
  ------WebKitFormBoundaryOmz20xyMCkE27rN7
  Content-Disposition: form-data; name="file"; filename="image.jpg"
  Content-Type: image/jpeg
  
  
  FILE_DATA
  ------WebKitFormBoundaryOmz20xyMCkE27rN7
  </code></pre>
  
  <p>I am using</p>
  
  <pre class="lang-js prettyprint-override"><code>const formData = new FormData();
  const data = new Blob([JSON.stringify({
          description: 'description',
        })], {
          type: 'application/json'
        });
  formData.set('data', data);
  formData.set('file', file);
  </code></pre>
  
  <p>it generate</p>
  
  <pre><code>------WebKitFormBoundaryOmz20xyMCkE27rN7
  Content-Disposition: form-data; name="data"; filename="blob"
  Content-Type: application/json
  
  {
    "description": "description"
  }
  ------WebKitFormBoundaryOmz20xyMCkE27rN7
  Content-Disposition: form-data; name="file"; filename="image.jpg"
  Content-Type: image/jpeg
  
  
  FILE_DATA
  ------WebKitFormBoundaryOmz20xyMCkE27rN7
  </code></pre>
  
  <p>As you can see we have a <code>filename="blob"</code> in JSON part , I want to remove it</p>
  
  <p>I want to have a <code>data</code> field in my multipart data not a <code>data</code> file</p>