Request: formData() method

{{APIRef("Fetch API")}}{{AvailableInWorkers}}

The formData() method of the {{domxref("Request")}} interface reads the request body and returns it as a promise that resolves with a {{domxref("FormData")}} object.

Syntax

formData()

Parameters

None.

Return value

A {{jsxref("Promise")}} that resolves with a {{domxref("FormData")}} object.

Exceptions

• {{jsxref("TypeError")}}
  • : Thrown for one of the following reasons:
    • The request body is disturbed or locked.
    • There was an error decoding the body content (for example, because the {{httpheader("Content-Encoding")}} header is incorrect).
    • The {{glossary("MIME")}} type of the body cannot be determined from the {{httpheader("Content-Type")}} headers included in the request, or is not application/x-www-form-urlencoded or multipart/form-data.
    • The body cannot be parsed as a FormData object.

Examples

const formData = new FormData();
const fileField = document.querySelector('input[type="file"]');

formData.append("username", "abc123");
formData.append("avatar", fileField.files[0]);

const request = new Request("/myEndpoint", {
  method: "POST",
  body: formData,
});

request.formData().then((data) => {
  // do something with the formdata sent in the request
});

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{domxref("Response.formData()")}}