fix: improve props spreading logic (#10574)

.changeset/three-papayas-buy.md

@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+fix: improve props spreading logic

packages/svelte/src/internal/client/render.js

@@ -2337,14 +2337,7 @@ const rest_props_handler = {
 		return key in target.props;
 	},
 	ownKeys(target) {
-		/** @type {Array<string | symbol>} */
+		return Reflect.ownKeys(target.props).filter((key) => !target.exclude.includes(key));
-		const keys = [];
-
-		for (let key in target.props) {
-			if (!target.exclude.includes(key)) keys.push(key);
-		}
-
-		return keys;
 	}
 };
 

packages/svelte/tests/runtime-runes/samples/spread-props/Button.svelte

@@ -0,0 +1,7 @@
+<script>
+	let { ...props } = $props();
+</script>
+
+<button {...props}>
+	Hello world
+</button>

packages/svelte/tests/runtime-runes/samples/spread-props/_config.js

@@ -0,0 +1,10 @@
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		assert.htmlEqual(
+			target.innerHTML,
+			`<button data-attr="">Hello world</button><button data-attr="">Hello world</button>`
+		);
+	}
+});

packages/svelte/tests/runtime-runes/samples/spread-props/main.svelte

@@ -0,0 +1,16 @@
+<script>
+	import Button from "./Button.svelte";
+
+	const attrs = {};
+
+	Object.defineProperty(attrs, "data-attr", {
+		value: "",
+		enumerable: true
+	});
+</script>
+
+<button {...attrs}>
+	Hello world
+</button>
+
+<Button {...attrs} />