breaking: remove Node polyfills (and by extension support for Node 18) (#14732)

* breaking: remove Node polyfills (and by extension support for Node 18)

* remove other references to node 18

* format

---------

Co-authored-by: Tee Ming <[email protected]>

Author: Rich-Harris

.changeset/busy-mails-clean.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-vercel': major
+---
+
+breaking: remove Node polyfills (and by extension support for Node 18)

documentation/docs/25-build-and-deploy/90-adapter-vercel.md

@@ -42,7 +42,7 @@ export const config = {
 
 The following options apply to all functions:
 
-- `runtime`: `'edge'`, `'nodejs18.x'`, `'nodejs20.x'` or `'nodejs22.x'`. By default, the adapter will select the `'nodejs<version>.x'` corresponding to the Node version your project is configured to use on the Vercel dashboard
+- `runtime`: `'edge'`, `'nodejs20.x'` or `'nodejs22.x'`. By default, the adapter will select the `'nodejs<version>.x'` corresponding to the Node version your project is configured to use on the Vercel dashboard
   > [!NOTE] This option is deprecated and will be removed in a future version, at which point all your functions will use whichever Node version is specified in the project configuration on Vercel
 - `regions`: an array of [edge network regions](https://vercel.com/docs/concepts/edge-network/regions) (defaulting to `["iad1"]` for serverless functions) or `'all'` if `runtime` is `edge` (its default). Note that multiple regions for serverless functions are only supported on Enterprise plans
 - `split`: if `true`, causes a route to be deployed as an individual function. If `split` is set to `true` at the adapter level, all routes will be deployed as individual functions

packages/adapter-vercel/files/serverless.js

@@ -1,11 +1,8 @@
-import { installPolyfills } from '@sveltejs/kit/node/polyfills';
 import { createReadableStream } from '@sveltejs/kit/node';
 import { Server } from 'SERVER';
 import { manifest } from 'MANIFEST';
 import process from 'node:process';
 
-installPolyfills();
-
 const server = new Server(manifest);
 
 await server.init({

packages/adapter-vercel/index.js

@@ -32,9 +32,9 @@ const get_default_runtime = () => {
 	// Also means we're not on the hook for updating the adapter every time a new Node
 	// version is added to Vercel.
 	if (!process.env.VERCEL) {
-		if (major < 18 || major > 22) {
+		if (major < 20 || major > 22) {
 			throw new Error(
-				`Building locally with unsupported Node.js version: ${process.version}. Please use Node 18, 20 or 22 to build your project, or explicitly specify a runtime in your adapter configuration.`
+				`Building locally with unsupported Node.js version: ${process.version}. Please use Node 20 or 22 to build your project, or explicitly specify a runtime in your adapter configuration.`
 			);
 		}
 
@@ -305,9 +305,9 @@ const plugin = function (defaults = {}) {
 				}
 
 				const node_runtime = /nodejs([0-9]+)\.x/.exec(runtime);
-				if (runtime !== 'edge' && (!node_runtime || parseInt(node_runtime[1]) < 18)) {
+				if (runtime !== 'edge' && (!node_runtime || parseInt(node_runtime[1]) < 20)) {
 					throw new Error(
-						`Invalid runtime '${runtime}' for route ${route.id}. Valid runtimes are 'edge' and 'nodejs18.x' or higher ` +
+						`Invalid runtime '${runtime}' for route ${route.id}. Valid runtimes are 'edge' and 'nodejs20.x' or higher ` +
 							'(see the Node.js Version section in your Vercel project settings for info on the currently supported versions).'
 					);
 				}

packages/adapter-vercel/package.json

@@ -52,5 +52,8 @@
 	},
 	"peerDependencies": {
 		"@sveltejs/kit": "^2.4.0"
+	},
+	"engines": {
+		"node": ">=20.0"
 	}
 }