Provides a way to easily construct a set of key/value pairs representing form fields and their values, which can then be easily sent using the XMLHttpRequest.send() method. It uses the same format a form would use if the encoding type were set to "multipart/form-data".
delete(name: string): void
get(name: string): FormDataEntryValue | null
getAll(name: string): FormDataEntryValue[]
has(name: string): boolean