HTMLFormElement: enctype property

The HTMLFormElement.enctype property is the MIME type of content that is used to submit the form to the server. Possible values are:

• application/x-www-form-urlencoded: The initial default type.
• multipart/form-data: The type that allows file <input> element(s) to upload file data.
• text/plain: Ambiguous format, human-readable content not reliably interpretable by computer.

This value can be overridden by a formenctype attribute on a <button> or <input> element.

form.enctype = "application/x-www-form-urlencoded";