Response: formData() method

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨April 2021⁩.

Note: This feature is available in Web Workers.

The formData() method of the Response interface takes a Response stream and reads it to completion. It returns a promise that resolves with a FormData object.

Note: This is mainly relevant to service workers. If a user submits a form and a service worker intercepts the request, you could for example call formData() on it to obtain a key-value map, modify some fields, then send the form onwards to the server (or use it locally).

Syntax

formData()

TypeError

Thrown for one of the following reasons:

The response body is disturbed or locked.
There was an error decoding the body content (for example, because the Content-Encoding header is incorrect).
The MIME type of the body cannot be determined from the Content-Type headers included in the response, or is not application/x-www-form-urlencoded or multipart/form-data.
The body cannot be parsed as a FormData object.