feat: add signal property to request (#14715)

* add signal

* test

* changeset

Author: PatrickG

.changeset/gentle-stars-repair.md

@@ -0,0 +1,6 @@
+---
+'@sveltejs/kit': minor
+'@sveltejs/adapter-node': minor
+---
+
+feat: add [`signal`](https://developer.mozilla.org/en-US/docs/Web/API/Request/signal) property to request

packages/kit/src/exports/node/index.js

@@ -120,11 +120,25 @@ export async function getRequest({ request, base, bodySizeLimit }) {
 		delete headers[':scheme'];
 	}
 
+	// TODO: Whenever Node >=22 is minimum supported version, we can use `request.readableAborted`
+	// @see https://github.com/nodejs/node/blob/5cf3c3e24c7257a0c6192ed8ef71efec8ddac22b/lib/internal/streams/readable.js#L1443-L1453
+	const controller = new AbortController();
+	let errored = false;
+	let end_emitted = false;
+	request.once('error', () => (errored = true));
+	request.once('end', () => (end_emitted = true));
+	request.once('close', () => {
+		if ((errored || request.destroyed) && !end_emitted) {
+			controller.abort();
+		}
+	});
+
 	return new Request(base + request.url, {
 		// @ts-expect-error
 		duplex: 'half',
 		method: request.method,
 		headers: Object.entries(headers),
+		signal: controller.signal,
 		body:
 			request.method === 'GET' || request.method === 'HEAD'
 				? undefined

packages/kit/test/apps/dev-only/src/routes/request-abort/+page.svelte

@@ -0,0 +1,20 @@
+<script>
+	import { onMount } from 'svelte';
+
+	let result;
+
+	function test_abort() {
+		const controller = new AbortController();
+		fetch('/request-abort', { method: 'POST', signal: controller.signal }).then((r) => r.json());
+		setTimeout(() => {
+			controller.abort();
+			fetch('/request-abort', { headers: { accept: 'application/json' } }).then(
+				async (r) => (result = await r.json())
+			);
+		}, 100);
+	}
+
+	onMount(test_abort);
+</script>
+
+<pre>{JSON.stringify(result)}</pre>

packages/kit/test/apps/dev-only/src/routes/request-abort/+server.js

@@ -0,0 +1,15 @@
+import { json } from '@sveltejs/kit';
+
+let aborted = false;
+
+/** @type {import('@sveltejs/kit').RequestHandler} */
+export function GET() {
+	return json({ aborted });
+}
+
+/** @type {import('@sveltejs/kit').RequestHandler} */
+export async function POST({ request }) {
+	request.signal.addEventListener('abort', () => (aborted = true));
+	await new Promise((r) => setTimeout(r, 1000));
+	return json({ ok: true });
+}

packages/kit/test/apps/dev-only/test/test.js

@@ -172,3 +172,13 @@ test.describe('Vite', () => {
 		expect(manifest).toHaveProperty('optimized.e2e-test-dep-hooks');
 	});
 });
+
+test.describe('request abort', () => {
+	test.skip(({ javaScriptEnabled }) => !process.env.DEV || !javaScriptEnabled);
+
+	test('request.signal fires abort event', async ({ page }) => {
+		await page.goto('/request-abort');
+		await page.waitForTimeout(200);
+		expect(await page.innerText('pre')).toBe('{"aborted":true}');
+	});
+});