transform assertions

packages/svelte/src/compiler/phases/3-transform/client/visitors/global.js

@@ -101,5 +101,13 @@ export const global_visitors = {
 				return b.call(b.thunk(b.block(statements)));
 			}
 		}
+	},
+	// @ts-expect-error
+	TSAsExpression(node, context) {
+		return context.visit(node.expression);
+	},
+	// @ts-expect-error
+	TSNonNullExpression(node, context) {
+		return context.visit(node.expression);
 	}
 };

packages/svelte/tests/runtime-runes/samples/typescript-in-event-handler/_config.js

@@ -0,0 +1,11 @@
+import { test } from '../../test';
+
+export default test({
+	html: '<button>clicks: 0</button>',
+
+	async test({ assert, target }) {
+		const btn = target.querySelector('button');
+		await btn?.click();
+		assert.htmlEqual(target.innerHTML, `<button>clicks: 1</button>`);
+	}
+});

packages/svelte/tests/runtime-runes/samples/typescript-in-event-handler/main.svelte

@@ -0,0 +1,10 @@
+<script>
+	let count = $state(0);
+</script>
+
+<button
+	on:click={(e: MouseEvent) => {
+		const next: number = count + 1;
+		count = next! as number;
+	}}
+>clicks: {count}</button>