feat: add preact-ssr-prepass (#9524)

* feat: add preact-ssr-prepass

* added more info to changelog

* fix example in changelog

* fix changelog description

* fix tab in code of changelog

* Update .changeset/blue-bobcats-remain.md

---------

Co-authored-by: Florian Lefebvre <[email protected]>

.changeset/blue-bobcats-remain.md

@@ -0,0 +1,21 @@
+---
+"@astrojs/preact": minor
+---
+
+Allows rendering lazy components.
+
+You can now use [lazy components](https://preactjs.com/guide/v10/switching-to-preact/#suspense-experimental) with Suspense:
+
+``` jsx
+import { lazy, Suspense } from 'preact/compat';
+
+const HeavyComponent= lazy(() => import('./HeavyComponent'));
+
+const Component = () => {
+  return (
+      <Suspense fallback={<p>Loading...</p>}>
+        <HeavyComponent foo="bar" />
+      </Suspense>
+    );
+};
+```

examples/framework-preact/src/components/Counter.css

@@ -5,7 +5,3 @@
 	margin-top: 2em;
 	place-items: center;
 }
-
-.counter-message {
-	text-align: center;
-}

examples/framework-preact/src/components/Counter.tsx

@@ -1,6 +1,10 @@
 import { h, Fragment } from 'preact';
+import { lazy, Suspense } from 'preact/compat';
 import './Counter.css';
 
+const Message = lazy(async () => import('./Message'));
+const Fallback = () => <p>Loading...</p>;
+
 export default function Counter({ children, count }) {
 	const add = () => count.value++;
 	const subtract = () => count.value--;
@@ -12,7 +16,9 @@ export default function Counter({ children, count }) {
 				<pre>{count}</pre>
 				<button onClick={add}>+</button>
 			</div>
-			<div class="counter-message">{children}</div>
+			<Suspense fallback={Fallback}>
+				<Message>{children}</Message>
+			</Suspense>
 		</>
 	);
 }

examples/framework-preact/src/components/Message.css

@@ -0,0 +1,3 @@
+.message {
+	text-align: center;
+}

examples/framework-preact/src/components/Message.tsx

@@ -0,0 +1,5 @@
+import './Message.css';
+
+export default function Message({ children }) {
+	return <div class="message">{children}</div>;
+}

packages/astro/e2e/fixtures/preact-lazy-component/astro.config.mjs

@@ -0,0 +1,8 @@
+import { defineConfig } from 'astro/config';
+import preact from '@astrojs/preact';
+import mdx from '@astrojs/mdx';
+
+// https://astro.build/config
+export default defineConfig({
+	integrations: [preact(), mdx()],
+});

packages/astro/e2e/fixtures/preact-lazy-component/package.json

@@ -0,0 +1,11 @@
+{
+  "name": "@e2e/preact-lazy-component",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "@astrojs/mdx": "workspace:*",
+    "@astrojs/preact": "workspace:*",
+    "astro": "workspace:*",
+    "preact": "^10.15.1"
+  }
+}

packages/astro/e2e/fixtures/preact-lazy-component/src/components/Counter.css

@@ -0,0 +1,11 @@
+.counter {
+	display: grid;
+	font-size: 2em;
+	grid-template-columns: repeat(3, minmax(0, 1fr));
+	margin-top: 2em;
+	place-items: center;
+}
+
+.counter-message {
+	text-align: center;
+}

packages/astro/e2e/fixtures/preact-lazy-component/src/components/Counter.jsx

@@ -0,0 +1,25 @@
+import { h, Fragment } from 'preact';
+import { useState } from 'preact/hooks';
+import { Suspense, lazy } from 'preact/compat';
+import './Counter.css';
+
+const LazyCounterMessage = lazy(() => import('./CounterMessage'))
+
+export default function Counter({ children, count: initialCount, id }) {
+	const [count, setCount] = useState(initialCount);
+	const add = () => setCount((i) => i + 1);
+	const subtract = () => setCount((i) => i - 1);
+
+	return (
+		<>
+			<div id={id} className="counter">
+				<button className="decrement" onClick={subtract}>-</button>
+				<pre>{count}</pre>
+				<button className="increment" onClick={add}>+</button>
+			</div>
+			<Suspense fallback={<p>Load message...</p>}>
+				<LazyCounterMessage className="counter-message">{children}</LazyCounterMessage>
+			</Suspense>
+		</>
+	);
+}

packages/astro/e2e/fixtures/preact-lazy-component/src/components/CounterMessage.jsx

@@ -0,0 +1,5 @@
+const CounterMessage = (props) => {
+  return <div className={props.className}>{props.children}</div>
+}
+
+export default CounterMessage

packages/astro/e2e/fixtures/preact-lazy-component/src/components/JSXComponent.jsx

@@ -0,0 +1,5 @@
+import { h } from 'preact';
+
+export default function({ id }) {
+	return <div id={id}>Framework client:only component</div>
+}

packages/astro/e2e/fixtures/preact-lazy-component/src/components/Layout.astro

@@ -0,0 +1,4 @@
+<html>
+	<head><title>Preact component</title></head>
+	<body><slot></slot></body>
+</html>

packages/astro/e2e/fixtures/preact-lazy-component/src/pages/index.astro

@@ -0,0 +1,37 @@
+---
+import Counter from '../components/Counter.jsx';
+import PreactComponent from '../components/JSXComponent.jsx';
+
+const someProps = {
+	count: 0,
+};
+---
+
+<html>
+	<head>
+		<!-- Head Stuff -->
+	</head>
+	<body>
+		<Counter id="server-only" {...someProps}>
+			<h1>Hello, server!</h1>
+		</Counter>
+
+		<Counter id="client-idle" {...someProps} client:idle>
+			<h1>Hello, client:idle!</h1>
+		</Counter>
+
+		<Counter id="client-load" {...someProps} client:load>
+			<h1>Hello, client:load!</h1>
+		</Counter>
+
+		<Counter id="client-visible" {...someProps} client:visible>
+			<h1>Hello, client:visible!</h1>
+		</Counter>
+
+		<Counter id="client-media" {...someProps} client:media="(max-width: 50em)">
+			<h1>Hello, client:media!</h1>
+		</Counter>
+
+		<PreactComponent id="client-only" client:only="preact" />
+	</body>
+</html>

packages/astro/e2e/fixtures/preact-lazy-component/src/pages/mdx.mdx

@@ -0,0 +1,29 @@
+export { default } from '../components/Layout.astro';
+import Counter from '../components/Counter.jsx';
+import PreactComponent from '../components/JSXComponent.jsx';
+
+export const someProps = {
+	count: 0,
+};
+
+<Counter id="server-only" {...someProps}>
+	# Hello, server!
+</Counter>
+
+<Counter id="client-idle" {...someProps} client:idle>
+	# Hello, client:idle!
+</Counter>
+
+<Counter id="client-load" {...someProps} client:load>
+	# Hello, client:load!
+</Counter>
+
+<Counter id="client-visible" {...someProps} client:visible>
+	# Hello, client:visible!
+</Counter>
+
+<Counter id="client-media" {...someProps} client:media="(max-width: 50em)">
+	# Hello, client:media!
+</Counter>
+
+<PreactComponent id="client-only" client:only="preact" />

packages/astro/e2e/preact-lazy-component.test.js

@@ -0,0 +1,24 @@
+import { prepareTestFactory } from './shared-component-tests.js';
+
+const { test, createTests } = prepareTestFactory({ root: './fixtures/preact-lazy-component/' });
+
+const config = {
+	counterComponentFilePath: './src/components/Counter.jsx',
+	componentFilePath: './src/components/JSXComponent.jsx',
+};
+
+test.describe('Preact lazy components in Astro files', () => {
+	createTests({
+		...config,
+		pageUrl: '/',
+		pageSourceFilePath: './src/pages/index.astro',
+	});
+});
+
+test.describe('Preact lazy components in MDX files', () => {
+	createTests({
+		...config,
+		pageUrl: '/mdx/',
+		pageSourceFilePath: './src/pages/mdx.mdx',
+	});
+});

packages/integrations/preact/package.json

@@ -40,7 +40,8 @@
     "@preact/preset-vite": "^2.7.0",
     "@preact/signals": "^1.2.1",
     "babel-plugin-transform-hook-names": "^1.0.2",
-    "preact-render-to-string": "^6.3.1"
+    "preact-render-to-string": "^6.3.1",
+    "preact-ssr-prepass": "^1.2.1"
   },
   "devDependencies": {
     "astro": "workspace:*",

packages/integrations/preact/src/server.ts

@@ -1,5 +1,6 @@
 import type { AstroComponentMetadata } from 'astro';
 import { Component as BaseComponent, h, type VNode } from 'preact';
+import prepass from "preact-ssr-prepass";
 import { render } from 'preact-render-to-string';
 import { getContext } from './context.js';
 import { restoreSignalsOnProps, serializeSignals } from './signals.js';
@@ -11,7 +12,7 @@ const slotName = (str: string) => str.trim().replace(/[-_]([a-z])/g, (_, w) => w
 let originalConsoleError: typeof console.error;
 let consoleFilterRefs = 0;
 
-function check(this: RendererContext, Component: any, props: Record<string, any>, children: any) {
+async function check(this: RendererContext, Component: any, props: Record<string, any>, children: any) {
 	if (typeof Component !== 'function') return false;
 	if (Component.name === 'QwikComponent') return false;
 
@@ -23,7 +24,7 @@ function check(this: RendererContext, Component: any, props: Record<string, any>
 
 	try {
 		try {
-			const { html } = renderToStaticMarkup.call(this, Component, props, children, undefined);
+			const { html } = await renderToStaticMarkup.call(this, Component, props, children, undefined);
 			if (typeof html !== 'string') {
 				return false;
 			}
@@ -45,7 +46,7 @@ function shouldHydrate(metadata: AstroComponentMetadata | undefined) {
 	return metadata?.astroStaticSlot ? !!metadata.hydrate : true;
 }
 
-function renderToStaticMarkup(
+async function renderToStaticMarkup(
 	this: RendererContext,
 	Component: any,
 	props: Record<string, any>,
@@ -72,22 +73,20 @@ function renderToStaticMarkup(
 	const attrs: AstroPreactAttrs = {};
 	serializeSignals(ctx, props, attrs, propsMap);
 
-	const html = render(
-		h(
-			Component,
-			newProps,
-			children != null
-				? h(StaticHtml, {
-						hydrate: shouldHydrate(metadata),
-						value: children,
-					})
-				: children
-		) as VNode<any>
-	);
-	return {
-		attrs,
-		html,
-	};
+	const vNode: VNode<any> = h(
+		Component,
+		newProps,
+		children != null
+			? h(StaticHtml, {
+					hydrate: shouldHydrate(metadata),
+					value: children,
+				})
+			: children
+	)
+
+	await prepass(vNode)
+	const html = render(vNode);
+	return { attrs, html };
 }
 
 /**