Response

`Response.prototype.formData`

Takes a Response stream and reads it to completion, returning the result as a FormData object

Syntax

JavaScript

response.formData()

Return Value

A Promise that resolves to a FormData object

Examples

Basic Usage

const response = await fetch('/api/form')
const formData = await response.formData()
console.log(formData.get('name'))

Practical Example

const form = document.querySelector('form') as HTMLFormElement
const data = new FormData(form)
const res = await fetch('/api/submit', { method: 'POST', body: data })
const result = await res.formData()
console.log('Server response:', result.get('status'))

Advanced Usage

async function parseMultipart(response: Response) {
  const fd = await response.formData()
  const entries: Record<string, FormDataEntryValue> = {}
  fd.forEach((value, key) => { entries[key] = value })
  return entries
}

Understanding Response.prototype.formData

The Response.prototype.formData method in JavaScript takes a Response stream and reads it to completion, returning the result as a FormData object. It belongs to the Response object and is one of the most widely used methods for working with response values in modern JavaScript and TypeScript applications.

The method signature is response.formData(). When called, it returns a promise that resolves to a formdata object. Understanding when and how to use formData() helps you write more expressive, readable code.

Common use cases for Response.prototype.formData include data transformation, input validation, API response processing, and building reusable utility functions. It works well alongside related methods like fetch-response-json, fetch-response-text, fetch-formdata-constructor, enabling you to chain operations together for complex data manipulation pipelines.

Browser support for Response.prototype.formData is excellent across all modern browsers including Chrome, Firefox, Safari, and Edge. It is also fully supported in Node.js and Deno. For older environments, transpilation with Babel or a polyfill may be needed.