Summary
-------

I am trying to set my `FormData` properly using javascript.

I need to be able to upload `jpg/png`, but I might need to upload some other file types `pdf/csv` in the future using fetch.

Expected
--------

I expect it to append the data to the form

Error
-----

![image](https://user-images.githubusercontent.com/1866564/33804094-5692d432-ddd0-11e7-946a-da23914c6c8b.png)

Working
-------

This snippet is working fine:

```
const formData = new FormData(document.querySelector('form'));
formData.append("extraField", "This is some extra data, testing");

return fetch('http://localhost:8080/api/upload/multi', {
    method: 'POST',
    body: formData,
});

```

![image](https://user-images.githubusercontent.com/1866564/33804126-dd69b052-ddd0-11e7-8a5e-fa7885634069.png)

Not working
-----------

```
const formData = new FormData();
const input = document.querySelector('input[type="file"]');
formData.append('files', input.files);

```

![image](https://user-images.githubusercontent.com/1866564/33804284-49674122-ddd4-11e7-8426-d897fb022802.png)

Question
--------

Does `fetch` support multiple file upload natively?