chore: Update throttling example with user delays

packages/playground/src/app/demos/throttling/client.tsx

@@ -1,23 +1,102 @@
 'use client'
 
-import { parseAsString, useQueryState } from 'next-usequerystate'
+import { useQueryState } from 'next-usequerystate'
+import { useRouter } from 'next/navigation'
+import React from 'react'
+import { delayParser, queryParser } from './parsers'
+
+const autoFillMessage = `Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec a diam lectus. Sed sit amet ipsum mauris. Maecenas congue ligula ac quam viverra nec consectetur ante hendrerit. Donec et mollis dolor.`
 
 export function Client() {
-  const [q, setQ] = useQueryState(
-    'q',
-    parseAsString
-      .withOptions({ throttleMs: 350, shallow: false })
-      .withDefault('')
+  const [serverDelay, setServerDelay] = useQueryState('serverDelay', {
+    ...delayParser,
+    shallow: false
+  })
+  const [clientDelay, setClientDelay] = useQueryState(
+    'clientDelay',
+    delayParser
   )
+  const [q, setQ] = useQueryState('q', {
+    ...queryParser,
+    throttleMs: clientDelay,
+    shallow: false
+  })
+  const router = useRouter()
+
+  const timeoutRef = React.useRef<number>()
+  const [index, setIndex] = React.useState(0)
+
+  React.useEffect(() => {
+    if (index === 0) {
+      return
+    }
+    setQ(autoFillMessage.slice(0, index))
+    clearTimeout(timeoutRef.current)
+    if (index === autoFillMessage.length) {
+      return
+    }
+    timeoutRef.current = window.setTimeout(() => {
+      setIndex(i => Math.min(i + 1, autoFillMessage.length))
+    }, 80)
+  }, [index])
 
   return (
     <>
-      <input
-        value={q}
-        onChange={e => setQ(e.target.value)}
-        placeholder="Search"
-      />
-      <p>Query: {q || <em>empty</em>}</p>
+      <h2>Client</h2>
+      <div>
+        <label>Server latency simulation </label>
+        <select
+          value={serverDelay}
+          onChange={e =>
+            setServerDelay(parseInt(e.target.value)).then(() =>
+              router.refresh()
+            )
+          }
+        >
+          <option value="0">No delay</option>
+          <option value="100">100ms</option>
+          <option value="200">200ms</option>
+          <option value="500">500ms</option>
+          <option value="1000">1s</option>
+        </select>
+      </div>
+      <div>
+        <label>Throttle URL updates at </label>
+        <select
+          value={clientDelay}
+          onChange={e => setClientDelay(parseInt(e.target.value))}
+        >
+          <option value="50">Default (50ms)</option>
+          <option value="100">100ms</option>
+          <option value="200">200ms</option>
+          <option value="500">500ms</option>
+          <option value="1000">1s</option>
+        </select>
+      </div>
+      <br />
+      <div>
+        <label>Query </label>
+        <input
+          value={q}
+          onChange={e => setQ(e.target.value)}
+          placeholder="Search"
+        />
+        {timeoutRef.current ? (
+          <button
+            onClick={() => {
+              setIndex(0)
+              clearTimeout(timeoutRef.current)
+              timeoutRef.current = undefined
+              setQ(null)
+            }}
+          >
+            Cancel
+          </button>
+        ) : (
+          <button onClick={() => setIndex(1)}>Simulate typing</button>
+        )}
+        <p>Client state: {q || <em>empty</em>}</p>
+      </div>
     </>
   )
 }

packages/playground/src/app/demos/throttling/page.tsx

@@ -1,11 +1,35 @@
+import { setTimeout } from 'node:timers/promises'
 import { Suspense } from 'react'
 import { Client } from './client'
+import { delayParser, queryParser } from './parsers'
 
-export default function ThottlingDemoPage() {
+type PageParams = {
+  searchParams: {
+    q?: string | string[]
+    serverDelay?: string | string[]
+  }
+}
+
+export default async function ThottlingDemoPage({ searchParams }: PageParams) {
+  const serverDelay = delayParser.parseServerSide(searchParams.serverDelay)
+  const query = queryParser.parseServerSide(searchParams.q)
+  await setTimeout(serverDelay)
+  console.debug('Server query: %s', query)
   return (
     <>
-      <h1>Throttled counters</h1>
-      <p>Note: URL state updated are intentionally slowed down</p>
+      <h1>Throttling</h1>
+      <p>
+        Play with the various delays, and try throttling your network connection
+        in devtools.
+      </p>
+      <p>
+        When the client is faster to update the URL than the network is to
+        re-render the server components, the server may hang under the waterfall
+        of heavy load.
+      </p>
+      <h2>Server</h2>
+      <p>Server delay: {serverDelay} ms</p>
+      <p>Server query: {query}</p>
       <Suspense>
         <Client />
       </Suspense>

packages/playground/src/app/demos/throttling/parsers.ts

@@ -0,0 +1,4 @@
+import { parseAsInteger, parseAsString } from 'next-usequerystate/parsers'
+
+export const delayParser = parseAsInteger.withDefault(0)
+export const queryParser = parseAsString.withDefault('')