Enable named slots in renderers (#3652)

* feat: pass all slots to renderers

* refactor: pass `slots` as top-level props

* test: add named slot test for frameworks

* fix: nested hydration, slots that are not initially rendered

* test: add nested-recursive e2e test

* fix: render unmatched custom element children

* chore: update lockfile

* fix: unrendered slots for client:only

* fix(lit): ensure lit integration uses new slots API

* chore: add changeset

* chore: add changesets

* fix: lit slots

* feat: convert dash-case or snake_case slots to camelCase for JSX

* feat: remove tmpl special logic

* test: add slot components-in-markdown test

* refactor: prefer Object.entries.map() to for/of loop

Co-authored-by: Nate Moore <nate@astro.build>

5 files changed, 35 insertions, 10 deletions

diff --git a/packages/integrations/react/client-v17.js b/packages/integrations/react/client-v17.js
index 1dce34709..443109603 100644
--- a/packages/integrations/react/client-v17.js
+++ b/packages/integrations/react/client-v17.js
@@ -3,7 +3,10 @@ import { render, hydrate } from 'react-dom';
 import StaticHtml from './static-html.js';
 
 export default (element) =>
-	(Component, props, children, { client }) => {
+	(Component, props, { default: children, ...slotted }, { client }) => {
+		for (const [key, value] of Object.entries(slotted)) {
+			props[key] = createElement(StaticHtml, { value, name: key });
+		}
 		const componentEl = createElement(
 			Component,
 			props,
diff --git a/packages/integrations/react/client.js b/packages/integrations/react/client.js
index 2828d2cbe..b41d7845a 100644
--- a/packages/integrations/react/client.js
+++ b/packages/integrations/react/client.js
@@ -11,8 +11,11 @@ function isAlreadyHydrated(element) {
 }
 
 export default (element) =>
-	(Component, props, children, { client }) => {
+	(Component, props, { default: children, ...slotted }, { client }) => {
 		if (!element.hasAttribute('ssr')) return;
+		for (const [key, value] of Object.entries(slotted)) {
+			props[key] = createElement(StaticHtml, { value, name: key });
+		}
 		const componentEl = createElement(
 			Component,
 			props,
diff --git a/packages/integrations/react/server-v17.js b/packages/integrations/react/server-v17.js
index b48d7b6f4..5d747a832 100644
--- a/packages/integrations/react/server-v17.js
+++ b/packages/integrations/react/server-v17.js
@@ -2,6 +2,7 @@ import React from 'react';
 import ReactDOM from 'react-dom/server.js';
 import StaticHtml from './static-html.js';
 
+const slotName = str => str.trim().replace(/[-_]([a-z])/g, (_, w) => w.toUpperCase());
 const reactTypeof = Symbol.for('react.element');
 
 function errorIsComingFromPreactComponent(err) {
@@ -50,12 +51,20 @@ function check(Component, props, children) {
 	return isReactComponent;
 }
 
-function renderToStaticMarkup(Component, props, children, metadata) {
+function renderToStaticMarkup(Component, props, { default: children, ...slotted }, metadata) {
 	delete props['class'];
-	const vnode = React.createElement(Component, {
+	const slots = {};
+	for (const [key, value] of Object.entries(slotted)) {
+		const name = slotName(key);
+		slots[name] = React.createElement(StaticHtml, { value, name });
+	}
+	// Note: create newProps to avoid mutating `props` before they are serialized
+	const newProps = { 
 		...props,
+		...slots,
 		children: children != null ? React.createElement(StaticHtml, { value: children }) : undefined,
-	});
+	}
+	const vnode = React.createElement(Component, newProps);
 	let html;
 	if (metadata && metadata.hydrate) {
 		html = ReactDOM.renderToString(vnode);
diff --git a/packages/integrations/react/server.js b/packages/integrations/react/server.js
index 776901563..cda839a1c 100644
--- a/packages/integrations/react/server.js
+++ b/packages/integrations/react/server.js
@@ -2,6 +2,7 @@ import React from 'react';
 import ReactDOM from 'react-dom/server';
 import StaticHtml from './static-html.js';
 
+const slotName = str => str.trim().replace(/[-_]([a-z])/g, (_, w) => w.toUpperCase());
 const reactTypeof = Symbol.for('react.element');
 
 function errorIsComingFromPreactComponent(err) {
@@ -56,12 +57,20 @@ async function getNodeWritable() {
 	return Writable;
 }
 
-async function renderToStaticMarkup(Component, props, children, metadata) {
+async function renderToStaticMarkup(Component, props, { default: children, ...slotted }, metadata) {
 	delete props['class'];
-	const vnode = React.createElement(Component, {
+	const slots = {};
+	for (const [key, value] of Object.entries(slotted)) {
+		const name = slotName(key);
+		slots[name] = React.createElement(StaticHtml, { value, name });
+	}
+	// Note: create newProps to avoid mutating `props` before they are serialized
+	const newProps = { 
 		...props,
+		...slots,
 		children: children != null ? React.createElement(StaticHtml, { value: children }) : undefined,
-	});
+	}
+	const vnode = React.createElement(Component, newProps);
 	let html;
 	if (metadata && metadata.hydrate) {
 		html = ReactDOM.renderToString(vnode);
diff --git a/packages/integrations/react/static-html.js b/packages/integrations/react/static-html.js
index ecd76ae9b..9589aaed8 100644
--- a/packages/integrations/react/static-html.js
+++ b/packages/integrations/react/static-html.js
@@ -7,9 +7,10 @@ import { createElement as h } from 'react';
  * As a bonus, we can signal to React that this subtree is
  * entirely static and will never change via `shouldComponentUpdate`.
  */
-const StaticHtml = ({ value }) => {
+const StaticHtml = ({ value, name }) => {
 	if (!value) return null;
-	return h('astro-fragment', {
+	return h('astro-slot', {
+		name,
 		suppressHydrationWarning: true,
 		dangerouslySetInnerHTML: { __html: value },
 	});