The FormData.entries() method returns an iterator allowing to go through all key/value pairs contained in this object. The key of each pair is a USVString object; the value either a USVString, or a Blob.
The FormData.keys() method returns an iterator allowing to go through all keys contained in this object. The keys are USVString objects.
The FormData.values() method returns an iterator allowing to go through all values contained in this object. The values are USVString or Blob objects.