feat: serialize signals in object

packages/astro/test/fixtures/preact-component/src/components/SignalsInArray.jsx

@@ -3,6 +3,6 @@ import { h } from 'preact';
 export default ({ signalsArray }) => {
   return <div class="preact-signal-array">
 		<h1>{signalsArray[0]} {signalsArray[3]}</h1>
-		<p>{signalsArray[1].value}{signalsArray[2].value}{signalsArray[4].value}</p>
+		<p>{signalsArray[1].value}-{signalsArray[2].value}-{signalsArray[4].value}</p>
 	</div>
 }

packages/astro/test/fixtures/preact-component/src/components/SignalsInObject.jsx

@@ -0,0 +1,8 @@
+import { h } from 'preact';
+
+export default ({ signalsObject }) => {
+  return <div class="preact-signal-object">
+		<h1>{signalsObject.title}</h1>
+		<p>{signalsObject.counter.value}</p>
+	</div>
+}

packages/astro/test/fixtures/preact-component/src/pages/signals.astro

@@ -2,6 +2,7 @@
 import { signal } from '@preact/signals';
 import Signals from '../components/Signals';
 import SignalsInArray from '../components/SignalsInArray';
+import SignalsInObject from '../components/SignalsInObject';
 const count = signal(1);
 const secondCount = signal(2);
 ---
@@ -13,5 +14,6 @@ const secondCount = signal(2);
 		<Signals client:load count={count} />
 		<Signals client:load count={count} />
 		<SignalsInArray client:load signalsArray={["I'm not a signal", count, count, 12345, secondCount]} />
+		<SignalsInObject client:load signalsObject={{title:'I am a title', counter: count}} />
 	</body>
 </html>

packages/astro/test/preact-component.test.js

@@ -119,7 +119,25 @@ describe('Preact component', () => {
 			],
 		});
 
-		assert.equal($('.preact-signal-array h1').text(), "I'm not a signal 12345");
-		assert.equal($('.preact-signal-array p').text(), '112');
+		assert.equal(element.find('h1').text(), "I'm not a signal 12345");
+		assert.equal(element.find('p').text(), '1-1-2');
+	});
+
+	it('Can use signals in object', async () => {
+		const html = await fixture.readFile('/signals/index.html');
+		const $ = cheerio.load(html);
+		const element = $('.preact-signal-object');
+		assert.equal(element.length, 1);
+
+		const sigs1Raw = $($('astro-island')[3]).attr('data-preact-signals');
+
+		const sigs1 = JSON.parse(sigs1Raw);
+
+		assert.deepEqual(sigs1, {
+			signalsObject: [['p0', 'counter']],
+		});
+
+		assert.equal(element.find('h1').text(), "I am a title");
+		assert.equal(element.find('p').text(), '1');
 	});
 });

packages/integrations/preact/src/client.ts

@@ -23,13 +23,21 @@ export default (element: HTMLElement) =>
 			);
 			for (const [propName, signalId] of Object.entries(signals)) {
 				if (Array.isArray(signalId)) {
-					signalId.forEach(([id, indexInPropsArray]) => {
-						const [valueOfSignal, indexInProps] = props[propName][indexInPropsArray];
+					signalId.forEach(([id, indexOrKeyInProps]) => {
+						const mapValue = props[propName][indexOrKeyInProps];
+						let valueOfSignal = mapValue;
+
+						// not an property key
+						if(typeof indexOrKeyInProps !== 'string') {
+							valueOfSignal = mapValue[0];
+							indexOrKeyInProps = mapValue[1];
+						}
+
 						if (!sharedSignalMap.has(id)) {
 							const signalValue = signal(valueOfSignal);
 							sharedSignalMap.set(id, signalValue);
 						}
-						props[propName][indexInProps] = sharedSignalMap.get(id);
+						props[propName][indexOrKeyInProps] = sharedSignalMap.get(id);
 					});
 				} else {
 					if (!sharedSignalMap.has(signalId)) {

packages/integrations/preact/src/signals.ts

@@ -28,18 +28,24 @@ export function serializeSignals(
 	map: PropNameToSignalMap,
 ) {
 	// Check for signals
-	const signals: Record<string, string | [string, number][]> = {};
+	const signals: Record<string, string | [string, number | string][]> = {};
 	for (const [key, value] of Object.entries(props)) {
-		if (Array.isArray(value)) {
-			value.forEach((signal, index) => {
-				// find signals in array. The index is important!
+		const isPropArray = Array.isArray(value);
+		const isPropObject = !isSignal(value) && typeof props[key] === 'object' && !isPropArray;
+
+		if (isPropObject || isPropArray) {
+			const values = isPropObject ? Object.keys(props[key]) : value;
+			values.forEach((valueKey: number | string, valueIndex: number) => {
+				const signal = isPropObject ? props[key][valueKey] : valueKey;
 				if (isSignal(signal)) {
-					props[key] = props[key].map((v: SignalLike, i: number) =>
-						i === index ? [signal.peek(), i] : v,
-					);
-					map.set(key, [...((map.get(key) || []) as []), [signal, index]]);
+					const keyOrIndex = isPropObject ? valueKey.toString() : valueIndex;
+
+					props[key] = isPropObject
+						? Object.assign({}, props[key], { [keyOrIndex]: signal.peek() })
+						: props[key].map((v: SignalLike, i: number) => (i === valueIndex ? signal.peek() : v));
+					map.set(key, [...((map.get(key) || []) as []), [signal, keyOrIndex]]);
 
-					signals[key] = [...((signals[key] || []) as []), [getSignalId(ctx, signal), index]];
+					signals[key] = [...((signals[key] || []) as []), [getSignalId(ctx, signal), keyOrIndex]];
 				}
 			});
 		} else if (isSignal(value)) {

packages/integrations/preact/src/types.ts

@@ -7,7 +7,7 @@ export type SignalLike = {
 	peek(): any;
 };
 
-export type PropNameToSignalMap = Map<string, SignalLike | [SignalLike, number][]>;
+export type PropNameToSignalMap = Map<string, SignalLike | [SignalLike, number | string][]>;
 
 export type AstroPreactAttrs = {
 	['data-preact-signals']?: string;