drop support for Node 12

drop support for Node 12

BREAKING CHANGE: drop support for Node 12

.github/workflows/ci.yml

@@ -14,16 +14,16 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macOS-latest]
-        node: ["12.20.0", "14.13.1", "16.0.0"]
+        node: ["14.17", "16.0.0"]
         exclude:
           # On Windows, run tests with only the LTS environments.
           - os: windows-latest
-            node: "12.22.3"
+            node: "14.17"
           - os: windows-latest
             node: "16.0.0"
           # On macOS, run tests with only the LTS environments.
           - os: macOS-latest
-            node: "12.22.3"
+            node: "14.17"
           - os: macOS-latest
             node: "16.0.0"
 

README.md

@@ -88,21 +88,21 @@ See Jason Miller's [isomorphic-unfetch](https://www.npmjs.com/package/isomorphic
 - Stay consistent with `window.fetch` API.
 - Make conscious trade-off when following [WHATWG fetch spec][whatwg-fetch] and [stream spec](https://streams.spec.whatwg.org/) implementation details, document known differences.
 - Use native promise and async functions.
-- Use native Node streams for body, on both request and response.
+- Use web streams for body, on both request and response.
 - Decode content encoding (gzip/deflate/brotli) properly, and convert string output (such as `res.text()` and `res.json()`) to UTF-8 automatically.
-- Useful extensions such as redirect limit, response size limit, [explicit errors][error-handling.md] for troubleshooting.
 
 ## Difference from client-side fetch
 
 - See known differences:
+	- [As of v4.x](docs/v4-LIMITS.md)
 	- [As of v3.x](docs/v3-LIMITS.md)
 	- [As of v2.x](docs/v2-LIMITS.md)
 - If you happen to use a missing feature that `window.fetch` offers, feel free to open an issue.
 - Pull requests are welcomed too!
 
 ## Installation
 
-Current stable release (`3.x`) requires at least Node.js 12.20.0.
+Current beta release (`4.x`) requires at least Node.js 14.17.0.
 
 ```sh
 npm install node-fetch
@@ -169,6 +169,7 @@ import './fetch-polyfill'
 
 Using an old version of node-fetch? Check out the following files:
 
+- [3.x to 4.x upgrade guide](docs/v4-UPGRADE-GUIDE.md)
 - [2.x to 3.x upgrade guide](docs/v3-UPGRADE-GUIDE.md)
 - [1.x to 2.x upgrade guide](docs/v2-UPGRADE-GUIDE.md)
 - [Changelog](docs/CHANGELOG.md)
@@ -868,4 +869,4 @@ Thanks to [github/fetch](https://github.com/github/fetch) for providing a solid
 [error-handling.md]: https://github.com/node-fetch/node-fetch/blob/master/docs/ERROR-HANDLING.md
 [FormData]: https://developer.mozilla.org/en-US/docs/Web/API/FormData
 [Blob]: https://developer.mozilla.org/en-US/docs/Web/API/Blob
-[File]: https://developer.mozilla.org/en-US/docs/Web/API/File
+[File]: https://developer.mozilla.org/en-US/docs/Web/API/File

docs/v4-LIMITS.md

@@ -0,0 +1,30 @@
+Known differences
+=================
+
+*As of 4.x release*
+
+- Topics such as Cross-Origin, Content Security Policy, Mixed Content, Service Workers are ignored, given our server-side context.
+
+- On the upside, there are no forbidden headers.
+
+- `res.url` contains the final url when following redirects.
+
+- For convenience, `res.body` is a Node.js [Readable stream][readable-stream], so decoding can be handled independently.
+
+- Similarly, `req.body` can either be `null`, a buffer or a Readable stream.
+
+- Also, you can handle rejected fetch requests through checking `err.type` and `err.code`. See [ERROR-HANDLING.md][] for more info.
+
+- Only support `res.text()`, `res.json()`, `res.blob()`, `res.arraybuffer()`, `res.buffer()`
+
+- There is currently no built-in caching, as server-side caching varies by use-cases.
+
+- Current implementation lacks server-side cookie store, you will need to extract `Set-Cookie` headers manually.
+
+- If you are using `res.clone()` and writing an isomorphic app, note that stream on Node.js has a smaller internal buffer size (16Kb, aka `highWaterMark`) from client-side browsers (>1Mb, not consistent across browsers). Learn [how to get around this][highwatermark-fix].
+
+- Because Node.js stream doesn't expose a [*disturbed*](https://fetch.spec.whatwg.org/#concept-readablestream-disturbed) property like Stream spec, using a consumed stream for `new Response(body)` will not set `bodyUsed` flag correctly.
+
+[readable-stream]: https://nodejs.org/api/stream.html#stream_readable_streams
+[ERROR-HANDLING.md]: https://github.com/node-fetch/node-fetch/blob/master/docs/ERROR-HANDLING.md
+[highwatermark-fix]: https://github.com/node-fetch/node-fetch/blob/master/README.md#custom-highwatermark

docs/v4-UPGRADE-GUIDE.md

@@ -0,0 +1,89 @@
+# Upgrade to node-fetch v3.x
+
+node-fetch v4.x brings about many changes that increase the compliance of
+WHATWG's [Fetch Standard][whatwg-fetch]. However, many of these changes mean
+that apps written for earlier version needs to be updated to work with
+node-fetch v3.x and be conformant with the Fetch Standard. This document helps
+you make this transition.
+
+Note that this document is not an exhaustive list of all changes made in v3.x,
+but rather that of the most important breaking changes. See our releases for
+other comparatively minor modifications.
+
+---
+
+## Minimum supported Node.js version is now 14.17
+
+Node.js 12 ends long time support in April 2022, we have decided that
+node-fetch v4 will drop support for Node.js 14.17 and below (which were
+previously supported). We strongly encourage you to upgrade if you still haven't
+done so. Check out the Node.js official [LTS plan] for more information.
+
+
+#### Why 14.17 and not 14.x?
+fetch is built around AbortController & AbortSignal in mind. v14.17 is the first
+version that added support for passing in a AbortSignal into `http.request()`
+We wish to use this feature and pass it along to the request.
+
+Request is also required to have a AbortSignal as a property.
+
+## Removed functionalities.
+
+We strive harder to match the spec, so that you can expect the same functionality
+across different environments to work the same wherever you are. That meant that
+some node-fetch only features had to go away.
+
+- Deprecated `response.buffer()` have been removed
+- The node-fetch only `size` limit option have been removed.
+- The `form-data` package have been removed in favor of a spec'ed one instead
+  `import { FormData } from 'node-fetch'`.
+
+## Headers class have been swapped out for the `fetch-headers` package
+We have had a own Headers class that have extended the `URLSearchParams` and
+brought all of the features of URLSearchParams into the Headers, This is not OK.
+The `fetch-headers` package have been broken out into a separate package for
+others to use who only wish to use this.
+This `fetch-headers` also runs all test against WPT, same test run by browsers
+to make sure it work as it should.
+
+Noticeable differences are:
+- `headers.raw()` is no longer possible to use.
+- `headers.getAll()` is no longer possible to use.
+- `content-encoding` is no longer normalized to all lowercase letters.
+
+## The `.body` stream have changed.
+Many have long wished for fetch to be built in right into NodeJS. But it's built
+up by so many peaces. One of the requirements is that it uses web streams instead
+of Node streams. We would never thought that NodeJS would ever add this when we
+first started this project and would only complicate things such as writing files
+to the filesystem. But now here they are built right into NodeJS!
+
+The `response.body` and `request.body` is now a whatwg stream instead of a Node
+stream.
+
+We use built in `node:stream/web` whenever it's available and fallback to using
+`web-streams-polyfill` when it's not available thanks to top level await for
+conditional imports.
+
+if you still need it to be a Node stream then you can use either
+[stream.Readable.from()](fromIterable) or [stream.Readable.fromWeb](fromWeb)
+
+Alternative you can go the other way around and convert your node streams to web
+stream
+```js
+import stream from 'node:stream'
+import { CompressionStream } from 'node:stream/web'
+import fs from 'node:fs'
+
+const writable = fs.createWriteStream('sample.bin')
+const writableStream = stream.Writable.toWeb(writable)
+
+new Response('abc').body
+  .pipeThrough(new CompressionStream('gzip'))
+  .pipeTo(writableStream)
+```
+
+
+
+[fromIterable]: https://nodejs.org/dist/latest-v17.x/docs/api/stream.html#streamreadablefromiterable-options
+[fromWeb]: https://nodejs.org/dist/latest-v17.x/docs/api/stream.html#streamreadablefromwebreadablestream-options

package.json

@@ -11,7 +11,7 @@
   ],
   "types": "./@types/index.d.ts",
   "engines": {
-    "node": "^12.20.0 || ^14.13.1 || >=16.0.0"
+    "node": "^14.17.1 || >=16.0.0"
   },
   "scripts": {
     "test": "mocha",