feat: use comments instead of element as marker

src/client.js

@@ -1,52 +1,58 @@
 /* eslint-disable no-var, key-spacing, object-curly-spacing, prefer-arrow-callback, semi, keyword-spacing */
 
-/**
- * @param {number} c Total number of hydration islands
- */
-function initPreactIslands(c) {
-	var el = document.currentScript.parentNode;
-	if (!document.getElementById('praect-island-style')) {
-		var s = document.createElement('style');
-		s.id = 'preact-island-style';
-		s.textContent = 'preact-island{display:contents}';
-		document.head.appendChild(s);
-	}
-	var o = new MutationObserver(function (m) {
-		for (var i = 0; i < m.length; i++) {
-			var added = m[i].addedNodes;
-			for (var j = 0; j < added.length; j++) {
-				if (added[j].nodeType !== 1) continue;
-				var id = added[j].getAttribute('data-target');
-				var target = document.querySelector('[data-id="' + id + '"]');
-				if (target) {
-					while (target.firstChild !== null) {
-						target.removeChild(target.firstChild);
-					}
-					while (added[j].firstChild !== null) {
-						target.appendChild(added[j].firstChild);
+function initPreactIslandElement() {
+	class PreactIslandElement extends HTMLElement {
+		connectedCallback() {
+			if (!this.isConnected) return;
+
+			let i = this.getAttribute('data-target');
+			if (!i) return;
+
+			var d = this;
+			function f(el) {
+				var a = [];
+				for (var j = 0; j < el.childNodes.length; j++) {
+					var n = el.childNodes[j];
+					if (n.nodeType === 8) {
+						a.push(n);
+					} else {
+						a.push(...f(n));
 					}
-					target.hydrate = true;
 				}
-				if (--c === 0) {
-					o.disconnect();
-					el.parentNode.removeChild(el);
+				return a;
+			}
+			var s, e;
+			for (var n of f(document)) {
+				if (n.data == 'preact-island:' + i) s = n;
+				else if (n.data == '/preact-island:' + i) e = n;
+				if (s && e) break;
+			}
+			if (s && e) {
+				var p = e.previousSibling;
+				for (; p != s; ) {
+					if (!p || p == s) break;
+
+					e.parentNode.removeChild(p);
+					p = e.previousSibling;
+				}
+				for (; d.firstChild; ) {
+					e.parentNode.insertBefore(d.firstChild, e);
 				}
+				d.parentNode.removeChild(d);
 			}
 		}
-	});
-	o.observe(el, { childList: true });
+	}
+
+	customElements.define('preact-island', PreactIslandElement);
 }
 
-const fn = initPreactIslands.toString();
+const fn = initPreactIslandElement.toString();
 const INIT_SCRIPT = fn
 	.slice(fn.indexOf('{') + 1, fn.lastIndexOf('}'))
 	.replace(/\n\s+/gm, '');
 
-/**
- * @param {number} total
- */
-export function createInitScript(total) {
-	return `<script>(function(){var c=${total};${INIT_SCRIPT}}())</script>`;
+export function createInitScript() {
+	return `<script>(function(){${INIT_SCRIPT}}())</script>`;
 }
 
 /**
@@ -55,5 +61,5 @@ export function createInitScript(total) {
  * @returns {string}
  */
 export function createSubtree(id, content) {
-	return `<div data-target="${id}">${content}</div>`;
+	return `<preact-island hidden data-target="${id}">${content}</preact-island>`;
 }

src/index.d.ts

@@ -15,6 +15,7 @@ export function renderToString(
 export function shallowRender(vnode: VNode, context?: any): string;
 
 export interface ChunkedOptions {
+	onError(error: unknown): void;
 	onWrite(chunk: string): void;
 	context?: any;
 	abortSignal?: AbortSignal;

src/index.js

@@ -106,7 +106,7 @@ function renderToString(vnode, context, opts) {
 
 /**
  * @param {VNode} vnode
- * @param {{ context?: any, onWrite: (str: string) => void, abortSignal?: AbortSignal }} options
+ * @param {{ context?: any, onError: (error: unknown) => void, onWrite: (str: string) => void, abortSignal?: AbortSignal }} options
  * @returns {Promise<void>}
  */
 export async function renderToChunks(vnode, { context, onWrite, abortSignal }) {
@@ -388,7 +388,7 @@ function _renderToString(
 						(component = susVNode[COMPONENT]) &&
 						component[CHILD_DID_SUSPEND]
 					) {
-						const id = 'preact-' + susVNode[MASK] + renderer.suspended.length;
+						const id = susVNode[MASK] + renderer.suspended.length;
 
 						const abortSignal = renderer.abortSignal;
 
@@ -408,22 +408,31 @@ function _renderToString(
 							selectValue,
 							vnode: susVNode,
 							promise: Promise.race([
-								error.then(() => {
-									if (abortSignal && abortSignal.aborted) {
-										return;
+								error.then(
+									() => {
+										if (abortSignal && abortSignal.aborted) {
+											return;
+										}
+
+										const str = _renderToString(
+											susVNode.props.children,
+											context,
+											isSvgMode,
+											selectValue,
+											susVNode,
+											renderer
+										);
+
+										renderer.onWrite(createSubtree(id, str));
+									},
+									(error) => {
+										// TODO: Abort and send hydration code snippet to client
+										// to attempt to recover during hydration
+										if (renderer.onError) {
+											renderer.onError(error);
+										}
 									}
-
-									const str = _renderToString(
-										susVNode.props.children,
-										context,
-										isSvgMode,
-										selectValue,
-										susVNode,
-										renderer
-									);
-
-									renderer.onWrite(createSubtree(id, str));
-								}),
+								),
 								race.promise
 							])
 						});
@@ -437,12 +446,12 @@ function _renderToString(
 							renderer
 						);
 
-						return `<preact-island data-id="${id}">${fallback}</preact-island>`;
+						return `<!--preact-island:${id}-->${fallback}<!--/preact-island:${id}-->`;
 					}
 				}
 			}
 
-			console.log('WOA', error, renderer);
+			// console.log('WOA', error, renderer);
 			let errorHook = options[CATCH_ERROR];
 			if (errorHook) errorHook(error, vnode);
 			return '';

src/stream-node.js

@@ -0,0 +1,61 @@
+import { PassThrough } from 'node:stream';
+
+import { renderToChunks } from './index';
+
+/**
+ * @typedef {object} RenderToPipeableStreamOptions
+ * @property {() => void} [onShellReady]
+ * @property {() => void} [onAllReady]
+ * @property {() => void} [onError]
+ */
+
+/**
+ * @param {VNode} vnode
+ * @param {RenderToPipeableStreamOptions} options
+ * @param {any} [context]
+ * @returns {{}}
+ */
+export function renderToPipeableStream(vnode, options, context) {
+	const encoder = new TextEncoder('utf-8');
+
+	const controller = new AbortController();
+	const stream = new PassThrough();
+
+	renderToChunks(vnode, {
+		context,
+		abortSignal: controller.signal,
+		onError: (error) => {
+			if (options.onError) {
+				options.onError(error);
+			}
+			controller.abort(error);
+		},
+		onWrite(s) {
+			stream.write(encoder.encode(s));
+		}
+	})
+		.then(() => {
+			options.onAllReady && options.onAllReady();
+			stream.end();
+		})
+		.catch((error) => {
+			stream.destroy(error);
+		});
+
+	Promise.resolve().then(() => {
+		options.onShellReady && options.onShellReady();
+	});
+
+	return {
+		abort() {
+			controller.abort();
+			stream.destroy(new Error('aborted'));
+		},
+		/**
+		 * @param {import("stream").Writable} writable
+		 */
+		pipe(writable) {
+			stream.pipe(writable, { end: true });
+		}
+	};
+}

src/stream.js

@@ -18,6 +18,10 @@ export function renderToReadableStream(vnode, context) {
 		start(controller) {
 			renderToChunks(vnode, {
 				context,
+				onError: (error) => {
+					allReady.reject(error);
+					controller.abort(error);
+				},
 				onWrite(s) {
 					controller.enqueue(encoder.encode(s));
 				}

test/compat-render-chunked.test.js

@@ -32,10 +32,10 @@ describe('renderToChunks', () => {
 		await promise;
 
 		expect(result).to.deep.equal([
-			'<div><preact-island data-id="preact-00">loading...</preact-island></div>',
+			'<div><!--preact-island:00-->loading...<!--/preact-island:00--></div>',
 			'<div hidden>',
-			createInitScript(1),
-			createSubtree('preact-00', '<p>it works</p>'),
+			createInitScript(),
+			createSubtree('00', '<p>it works</p>'),
 			'</div>'
 		]);
 	});
@@ -60,7 +60,7 @@ describe('renderToChunks', () => {
 		suspended.resolve();
 
 		expect(result).to.deep.equal([
-			'<div><preact-island data-id="preact-00">loading...</preact-island></div>',
+			'<div><!--preact-island:00-->loading...<!--/preact-island:00--></div>',
 			'<div hidden>',
 			createInitScript(1),
 			'</div>'

test/compat-stream-node.test.js

@@ -1,35 +1,76 @@
-/**
- * @param {ReadableStream} input
- */
-function createSink(input) {
-	const decoder = new TextDecoder('utf-8');
-	const queuingStrategy = new CountQueuingStrategy({ highWaterMark: 1 });
+import { PassThrough } from 'node:stream';
+import { h } from 'preact';
+import { expect } from 'chai';
+import { Suspense } from 'preact/compat';
+import { createSubtree, createInitScript } from '../src/client';
+import { renderToPipeableStream } from '../src/stream-node';
+import { Deferred } from '../src/util';
+import { createSuspender } from './utils';
 
+function streamToString(stream) {
+	const decoder = new TextDecoder();
 	const def = new Deferred();
-	const result = [];
-
-	const stream = new WritableStream(
-		{
-			// Implement the sink
-			write(chunk) {
-				result.push(decoder.decode(chunk));
-			},
-			close() {
-				def.resolve(result);
-			},
-			abort(err) {
-				def.reject(err);
-			}
-		},
-		queuingStrategy
-	);
+	stream.on('data', (chunk) => {
+		chunks.push(decoder.decode(chunk));
+	});
+	stream.on('error', (err) => def.reject(err));
+	stream.on('end', () => def.resolve(chunks));
+	const chunks = [];
+	return def;
+}
 
-	input.pipeTo(stream);
+/**
+ * @param {ReadableStream} input
+ */
+function createSink() {
+	const stream = new PassThrough();
+	const def = streamToString(stream);
 
 	return {
 		promise: def.promise,
 		stream
 	};
 }
 
-describe('', () => {});
+describe('renderToPipeableStream', () => {
+	it('should render non-suspended JSX in one go', async () => {
+		const sink = createSink();
+		const { pipe } = renderToPipeableStream(<div class="foo">bar</div>, {
+			onAllReady: () => {
+				pipe(sink.stream);
+			}
+		});
+		const result = await sink.promise;
+
+		expect(result).to.deep.equal(['<div class="foo">bar</div>']);
+	});
+
+	it('should render fallback + attach loaded subtree on suspend', async () => {
+		const { Suspender, suspended } = createSuspender();
+
+		const sink = createSink();
+		const { pipe } = renderToPipeableStream(
+			<div>
+				<Suspense fallback="loading...">
+					<Suspender />
+				</Suspense>
+			</div>,
+			{
+				onShellReady: () => {
+					pipe(sink.stream);
+				}
+			}
+		);
+		suspended.resolve();
+
+		const result = await sink.promise;
+
+		expect(result).to.deep.equal([
+			'<div><!--preact-island:00-->loading...<!--/preact-island:00--></div>',
+			'<div hidden>',
+			createInitScript(),
+			createSubtree('00', '<p>it works</p>'),
+			'</div>'
+		]);
+	});
+});