fix: correctly serialize Infinity as island props

.changeset/beige-rice-tap.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Support passing the values `Infinity` and `-Infinity` as island props. 

packages/astro/e2e/fixtures/pass-js/src/components/React.tsx

@@ -11,12 +11,14 @@ interface Props {
 	array: any[];
 	map: Map<string, string>;
 	set: Set<string>;
+	infinity: number;
+	negativeInfinity: number;
 }
 
 const isNode = typeof process !== 'undefined' && Object.prototype.toString.call(process) === '[object process]';
 
 /** a counter written in React */
-export default function Component({ undefined: undefinedProp, null: nullProp, boolean, number, string, bigint, object, array, map, set }: Props) {
+export default function Component({ undefined: undefinedProp, null: nullProp, boolean, number, string, bigint, object, array, map, set, infinity, negativeInfinity }: Props) {
 	// We are testing hydration, so don't return anything in the server.
 	if(isNode) {
 		return <div></div>
@@ -30,6 +32,10 @@ export default function Component({ undefined: undefinedProp, null: nullProp, bo
 			<span id="boolean-value">{boolean.toString()}</span>
 			<span id="number-type">{Object.prototype.toString.call(number)}</span>
 			<span id="number-value">{number.toString()}</span>
+			<span id="infinity-type">{Object.prototype.toString.call(infinity)}</span>
+			<span id="infinity-value">{infinity.toString()}</span>
+			<span id="negative-infinity-type">{Object.prototype.toString.call(negativeInfinity)}</span>
+			<span id="negative-infinity-value">{negativeInfinity.toString()}</span>
 			<span id="string-type">{Object.prototype.toString.call(string)}</span>
 			<span id="string-value">{string}</span>
 			<span id="bigint-type">{Object.prototype.toString.call(bigint)}</span>

packages/astro/e2e/fixtures/pass-js/src/pages/index.astro

@@ -42,6 +42,8 @@ set.add('test2');
 				array={[0, "foo"]}
 				map={map}
 				set={set}
+				infinity={Infinity}
+				negativeInfinity={-Infinity}
 			/>
 		</main>
 	</body>

packages/astro/e2e/pass-js.test.js

@@ -47,6 +47,22 @@ test.describe('Passing JS into client components', () => {
 		await expect(numberValue, 'is visible').toBeVisible();
 		await expect(numberValue).toHaveText('16');
 
+		const infinityType = page.locator('#infinity-type');
+		await expect(infinityType, 'is visible').toBeVisible();
+		await expect(infinityType).toHaveText('[object Number]');
+
+		const negativeInfinityType = page.locator('#negative-infinity-type');
+		await expect(negativeInfinityType, 'is visible').toBeVisible();
+		await expect(negativeInfinityType).toHaveText('[object Number]');
+
+		const infinityValue = page.locator('#infinity-value');
+		await expect(infinityValue, 'is visible').toBeVisible();
+		await expect(infinityValue).toHaveText('Infinity');
+
+		const negativeInfinityValue = page.locator('#negative-infinity-value');
+		await expect(negativeInfinityValue, 'is visible').toBeVisible();
+		await expect(negativeInfinityValue).toHaveText('-Infinity');
+
 		// string
 		const stringType = page.locator('#string-type');
 		await expect(stringType, 'is visible').toBeVisible();

packages/astro/src/runtime/server/astro-island.ts

@@ -29,6 +29,7 @@ declare const Astro: {
 		8: (value) => new Uint8Array(value),
 		9: (value) => new Uint16Array(value),
 		10: (value) => new Uint32Array(value),
+		11: (value) => Infinity * value,
 	};
 
 	// Not using JSON.parse reviver because it's bottom-up but we want top-down

packages/astro/src/runtime/server/serialize.ts

@@ -13,6 +13,7 @@ const PROP_TYPE = {
 	Uint8Array: 8,
 	Uint16Array: 9,
 	Uint32Array: 10,
+	Infinity: 11,
 };
 
 function serializeArray(
@@ -93,11 +94,17 @@ function convertToSerializedForm(
 		default: {
 			if (value !== null && typeof value === 'object') {
 				return [PROP_TYPE.Value, serializeObject(value, metadata, parents)];
-			} else if (value === undefined) {
+			}
+			if (value === Infinity) {
+				return [PROP_TYPE.Infinity, 1];
+			}
+			if (value === -Infinity) {
+				return [PROP_TYPE.Infinity, -1];
+			}
+			if (value === undefined) {
 				return [PROP_TYPE.Value];
-			} else {
-				return [PROP_TYPE.Value, value];
 			}
+			return [PROP_TYPE.Value, value];
 		}
 	}
 }

packages/astro/test/serialize.test.js

@@ -89,6 +89,11 @@ describe('serialize', () => {
 		const output = `{"a":[10,[1,2,3]]}`;
 		assert.equal(serializeProps(input), output);
 	});
+	it('serializes Infinity and -Infinity', () => {
+		const input = { a: Infinity, b: -Infinity };
+		const output = `{"a":[11,1],"b":[11,-1]}`;
+		assert.equal(serializeProps(input), output);
+	})
 	it('cannot serialize a cyclic reference', () => {
 		const a = {};
 		a.b = a;