Куда лить: <br/><input type='file' id='file' />
<a href='#' id='url'></a>
<script>
    file.onchange = async () => {
        url.innerHTML = url.href = "/" + await (await fetch('/upload', {
            method: "POST",
            headers: localStorage.authToken ? {Authorization: 'Bearer ' + localStorage.authToken} : {},
            body: file.files[0]
        })).text()
    }
</script>

<form action="/upload" method="post" enctype="multipart/form-data" id='form'>
  <input type="file" name="photo" id='photo'/>
</form>

<script>
    photo.onchange = async () => {
        fetch('/upload', {
            method: "POST",
            headers: localStorage.authToken ? {Authorization: 'Bearer ' + localStorage.authToken} : {},
            body: new FormData(form)
        })
    }
</script>