add sync external exercise

exercises/09.sync-external/02.solution/index.tsx

@@ -1,14 +1,28 @@
 import { useSyncExternalStore } from 'react'
 import * as ReactDOM from 'react-dom/client'
-import { makeMediaQueryStore } from './narrow-media-query'
 
-const narrowScreenStore = makeMediaQueryStore('(max-width: 600px)')
+export function makeMediaQueryStore(mediaQuery: string) {
+	function getSnapshot() {
+		return window.matchMedia(mediaQuery).matches
+	}
+
+	function subscribe(callback: () => void) {
+		const mediaQueryList = window.matchMedia(mediaQuery)
+		mediaQueryList.addEventListener('change', callback)
+		return () => {
+			mediaQueryList.removeEventListener('change', callback)
+		}
+	}
+
+	return function useMediaQuery() {
+		return useSyncExternalStore(subscribe, getSnapshot)
+	}
+}
+
+const useNarrowMediaQuery = makeMediaQueryStore('(max-width: 600px)')
 
 function NarrowScreenNotifier() {
-	const isNarrow = useSyncExternalStore(
-		narrowScreenStore.subscribe,
-		narrowScreenStore.getSnapshot,
-	)
+	const isNarrow = useNarrowMediaQuery()
 	return isNarrow ? 'You are on a narrow screen' : 'You are on a wide screen'
 }
 

exercises/09.sync-external/03.problem/README.mdx

@@ -0,0 +1 @@
+# Make Store Utility

exercises/09.sync-external/03.problem/index.tsx

@@ -0,0 +1,51 @@
+import { useSyncExternalStore } from 'react'
+import * as ReactDOM from 'react-dom/client'
+
+export function makeMediaQueryStore(mediaQuery: string) {
+	function getSnapshot() {
+		return window.matchMedia(mediaQuery).matches
+	}
+
+	function subscribe(callback: () => void) {
+		const mediaQueryList = window.matchMedia(mediaQuery)
+		mediaQueryList.addEventListener('change', callback)
+		return () => {
+			mediaQueryList.removeEventListener('change', callback)
+		}
+	}
+
+	return function useMediaQuery() {
+		return useSyncExternalStore(subscribe, getSnapshot)
+	}
+}
+
+const useNarrowMediaQuery = makeMediaQueryStore('(max-width: 600px)')
+
+function NarrowScreenNotifier() {
+	const isNarrow = useNarrowMediaQuery()
+	return isNarrow ? 'You are on a narrow screen' : 'You are on a wide screen'
+}
+
+function App() {
+	return (
+		<div>
+			<div>This is your narrow screen state:</div>
+			{/* 🐨 add a Suspense component around this with a fallback prop */}
+			<NarrowScreenNotifier />
+		</div>
+	)
+}
+
+const rootEl = document.createElement('div')
+document.body.append(rootEl)
+// 🦉 here's how we pretend we're server-rendering
+rootEl.innerHTML = (await import('react-dom/server')).renderToString(<App />)
+
+// 🦉 here's how we simulate a delay in hydrating with client-side js
+await new Promise(resolve => setTimeout(resolve, 1000))
+
+ReactDOM.hydrateRoot(rootEl, <App />, {
+	// 💯 if you want to silence the error add a onRecoverableError function here
+	// and if the error includes 'Missing getServerSnapshot' then return early
+	// otherwise log the error so you don't miss any other errors.
+})

exercises/09.sync-external/03.solution/README.mdx

@@ -0,0 +1 @@
+# Make Store Utility

exercises/09.sync-external/03.solution/index.tsx

@@ -0,0 +1,54 @@
+import { Suspense, useSyncExternalStore } from 'react'
+import * as ReactDOM from 'react-dom/client'
+
+export function makeMediaQueryStore(mediaQuery: string) {
+	function getSnapshot() {
+		return window.matchMedia(mediaQuery).matches
+	}
+
+	function subscribe(callback: () => void) {
+		const mediaQueryList = window.matchMedia(mediaQuery)
+		mediaQueryList.addEventListener('change', callback)
+		return () => {
+			mediaQueryList.removeEventListener('change', callback)
+		}
+	}
+
+	return function useMediaQuery() {
+		return useSyncExternalStore(subscribe, getSnapshot)
+	}
+}
+
+const useNarrowMediaQuery = makeMediaQueryStore('(max-width: 600px)')
+
+function NarrowScreenNotifier() {
+	const isNarrow = useNarrowMediaQuery()
+	return isNarrow ? 'You are on a narrow screen' : 'You are on a wide screen'
+}
+
+function App() {
+	return (
+		<div>
+			<div>This is your narrow screen state:</div>
+			<Suspense fallback="">
+				<NarrowScreenNotifier />
+			</Suspense>
+		</div>
+	)
+}
+
+const rootEl = document.createElement('div')
+document.body.append(rootEl)
+// 🦉 here's how we pretend we're server-rendering
+rootEl.innerHTML = (await import('react-dom/server')).renderToString(<App />)
+
+// 🦉 here's how we simulate a delay in hydrating with client-side js
+await new Promise(resolve => setTimeout(resolve, 1000))
+
+ReactDOM.hydrateRoot(rootEl, <App />, {
+	onRecoverableError(error) {
+		if (String(error).includes('Missing getServerSnapshot')) return
+
+		console.error(error)
+	},
+})