feat: server js fallthrough to page if handler doesn't exist

.changeset/spicy-rockets-ring.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+feat: server js fallthrough to page if method handler doesn't exist

packages/kit/src/runtime/server/respond.js

@@ -378,11 +378,8 @@ export async function respond(request, options, manifest, state) {
 			}
 
 			if (route) {
-				/** @type {Response} */
-				let response;
-
 				if (is_data_request) {
-					response = await render_data(
+					return await render_data(
 						event,
 						route,
 						options,
@@ -392,16 +389,26 @@ export async function respond(request, options, manifest, state) {
 						trailing_slash ?? 'never'
 					);
 				} else if (route.endpoint && (!route.page || is_endpoint_request(event))) {
-					response = await render_endpoint(event, await route.endpoint(), state);
+					const endpoint = await route.endpoint();
+					const response = await render_endpoint(event, endpoint, state);
+
+					// If endpoint doesn't have a handler for these methods, fall back to the page
+					if (
+						response.status === 405 &&
+						route.page &&
+						['HEAD', 'GET', 'POST'].includes(event.request.method)
+					) {
+						return await render_page(event, route.page, options, manifest, state, resolve_opts);
+					} else {
+						return response;
+					}
 				} else if (route.page) {
-					response = await render_page(event, route.page, options, manifest, state, resolve_opts);
+					return await render_page(event, route.page, options, manifest, state, resolve_opts);
 				} else {
 					// a route will always have a page or an endpoint, but TypeScript
 					// doesn't know that
 					throw new Error('This should never happen');
 				}
-
-				return response;
 			}
 
 			if (state.error) {

packages/kit/test/apps/basics/src/routes/routing/endpoint-fallthrough/+page.svelte

@@ -0,0 +1 @@
+<pre>Hello from the page!</pre>

packages/kit/test/apps/basics/test/server.test.js

@@ -199,6 +199,13 @@ test.describe('Endpoints', () => {
 		expect(response.status()).toBe(200);
 		expect(await response.text()).toBe('ok');
 	});
+
+	test('falls back to page if no matching handler found', async ({ request }) => {
+		const response = await request.get('/routing/endpoint-fallthrough');
+
+		expect(response.status()).toBe(200);
+		expect(await response.text()).toContain('Hello from the page!');
+	});
 });
 
 test.describe('Errors', () => {