feat(Body): Added support for BodyMixin.formData() and constructing bodies with FormData

@types/index.d.ts

@@ -95,6 +95,7 @@ export type BodyInit =
 	| Blob
 	| Buffer
 	| URLSearchParams
+	| FormData
 	| NodeJS.ReadableStream
 	| string;
 declare class BodyMixin {
@@ -106,6 +107,7 @@ declare class BodyMixin {
 
 	buffer(): Promise<Buffer>;
 	arrayBuffer(): Promise<ArrayBuffer>;
+	formData(): Promise<FormData>;
 	blob(): Promise<Blob>;
 	json(): Promise<unknown>;
 	text(): Promise<string>;

README.md

@@ -712,6 +712,8 @@ A boolean property for if this body has been consumed. Per the specs, a consumed
 
 #### body.arrayBuffer()
 
+#### body.formData()
+
 #### body.blob()
 
 #### body.json()
@@ -724,14 +726,6 @@ A boolean property for if this body has been consumed. Per the specs, a consumed
 
 Consume the body and return a promise that will resolve to one of these formats.
 
-#### body.buffer()
-
-<small>_(node-fetch extension)_</small>
-
-- Returns: `Promise<Buffer>`
-
-Consume the body and return a promise that will resolve to a Buffer.
-
 <a id="class-fetcherror"></a>
 
 ### Class: FetchError

docs/CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - other: Deprecated/Discourage [form-data](https://www.npmjs.com/package/form-data) and body.buffer() (#1212)
 - fix: Normalize `Body.body` into a `node:stream` (#924)
+- feat: Added support for `Body.formData()`
 
 ## v3.0.0
 

package.json

@@ -55,15 +55,15 @@
     "coveralls": "^3.1.0",
     "delay": "^5.0.0",
     "form-data": "^4.0.0",
-    "formdata-node": "^3.5.4",
     "mocha": "^8.3.2",
     "p-timeout": "^5.0.0",
     "tsd": "^0.14.0",
     "xo": "^0.39.1"
   },
   "dependencies": {
     "data-uri-to-buffer": "^3.0.1",
-    "fetch-blob": "^3.1.2"
+    "fetch-blob": "^3.1.2",
+    "formdata-polyfill": "^4.0.8"
   },
   "tsd": {
     "cwd": "@types",
@@ -91,6 +91,8 @@
       "unicorn/numeric-separators-style": 0,
       "unicorn/explicit-length-check": 0,
       "capitalized-comments": 0,
+      "node/no-unsupported-features/es-syntax": 0,
+      "no-fallthrough": 0,
       "@typescript-eslint/member-ordering": 0
     },
     "overrides": [

src/body.js

@@ -9,10 +9,10 @@ import Stream, {PassThrough} from 'stream';
 import {types, deprecate} from 'util';
 
 import Blob from 'fetch-blob';
+import {FormData, formDataToBlob} from 'formdata-polyfill/esm.min.js';
 
 import {FetchError} from './errors/fetch-error.js';
 import {FetchBaseError} from './errors/base.js';
-import {formDataIterator, getBoundary, getFormDataLength} from './utils/form-data.js';
 import {isBlob, isURLSearchParameters, isFormData} from './utils/is.js';
 
 const INTERNALS = Symbol('Body internals');
@@ -52,8 +52,8 @@ export default class Body {
 			// Body is stream
 		} else if (isFormData(body)) {
 			// Body is an instance of formdata-node
-			boundary = `nodefetchformdataboundary${getBoundary()}`;
-			body = Stream.Readable.from(formDataIterator(body, boundary));
+			body = formDataToBlob(body);
+			boundary = body.type.split('=')[1];
 		} else {
 			// None of the above
 			// coerce to string then buffer
@@ -105,6 +105,24 @@ export default class Body {
 		return buffer.slice(byteOffset, byteOffset + byteLength);
 	}
 
+	async formData() {
+		const ct = this.headers.get('content-type');
+
+		if (ct.startsWith('application/x-www-form-urlencoded')) {
+			const fd = new FormData();
+			const parameters = new URLSearchParams(await this.text());
+
+			for (const [name, value] of parameters) {
+				fd.append(name, value);
+			}
+
+			return fd;
+		}
+
+		const {toFormData} = await import('./utils/multipart-parser.js');
+		return toFormData(this.body, ct);
+	}
+
 	/**
 	 * Return raw response as Blob
 	 *
@@ -352,11 +370,6 @@ export const getTotalBytes = request => {
 		return body.hasKnownLength && body.hasKnownLength() ? body.getLengthSync() : null;
 	}
 
-	// Body is a spec-compliant FormData
-	if (isFormData(body)) {
-		return getFormDataLength(request[INTERNALS].boundary);
-	}
-
 	// Body is stream
 	return null;
 };

src/response.js

@@ -29,7 +29,7 @@ export default class Response extends Body {
 		const headers = new Headers(options.headers);
 
 		if (body !== null && !headers.has('Content-Type')) {
-			const contentType = extractContentType(body);
+			const contentType = extractContentType(body, this);
 			if (contentType) {
 				headers.append('Content-Type', contentType);
 			}