how to set filename in fetch file upload code example

Example: fetch file upload

const handleImageUpload = event => {
  const files = event.target.files
  const formData = new FormData()
  formData.append('myFile', files[0])

  fetch('/saveImage', {
    method: 'POST',
    body: formData
  })
  .then(response => response.json())
  .then(data => {
    console.log(data)
  })
  .catch(error => {
    console.error(error)
  })
}