Add the submitter value with name to formData for use:enhance

packages/kit/src/runtime/app/forms.js

@@ -51,6 +51,12 @@ export function enhance(form, submit = () => {}) {
 		);
 
 		const data = new FormData(form);
+
+		const submitter_name = event.submitter?.getAttribute('name');
+		if (submitter_name) {
+			data.append(submitter_name, event.submitter?.getAttribute('value') ?? '');
+		}
+
 		const controller = new AbortController();
 
 		let cancelled = false;

packages/kit/test/apps/basics/src/routes/actions/enhance/+page.server.js

@@ -21,5 +21,11 @@ export const actions = {
 	},
 	slow: async () => {
 		await new Promise((resolve) => setTimeout(resolve, 500));
+	},
+	submitter: async ({ request }) => {
+		const fields = await request.formData();
+		return {
+			result: 'submitter: ' + fields.get('submitter')
+		};
 	}
 };

packages/kit/test/apps/basics/src/routes/actions/enhance/+page.svelte

@@ -17,6 +17,7 @@
 	<input name="username" type="text" />
 	<button class="form1">Submit</button>
 	<button class="form1-register" formAction="?/register">Submit</button>
+	<button class="form1-submitter" formAction="?/submitter" name="submitter" value="foo">Submit</button>
 </form>
 
 <span class="count">{count}</span>

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

@@ -1865,6 +1865,21 @@ test.describe('Actions', () => {
 		);
 	});
 
+	test('use:enhance button with name', async ({ page, app }) => {
+		await page.goto('/actions/enhance');
+
+		expect(await page.textContent('pre.formdata1')).toBe(JSON.stringify(null));
+
+		await Promise.all([
+			page.waitForRequest((request) => request.url().includes('/actions/enhance')),
+			page.click('button.form1-submitter')
+		]);
+
+		await expect(page.locator('pre.formdata1')).toHaveText(
+			JSON.stringify({ result: 'submitter: foo' })
+		);
+	});
+
 	test('redirect', async ({ page }) => {
 		await page.goto('/actions/redirect');