{"id":3247,"date":"2026-08-17T09:50:58","date_gmt":"2026-08-17T00:50:58","guid":{"rendered":"https:\/\/qol-kk.com\/wp2\/?p=3247"},"modified":"2026-09-07T13:50:23","modified_gmt":"2026-09-07T04:50:23","slug":"20260816-00msv28g","status":"publish","type":"post","link":"https:\/\/qol-kk.com\/wp2\/blog\/2026\/08\/17\/20260816-00msv28g\/","title":{"rendered":"React 19 \u306e\u65b0\u6a5f\u80fd\u307e\u3068\u3081\uff08\u5165\u9580\uff09"},"content":{"rendered":"<style>\n.qol-article pre{\n  background:#1c2b33;\n  color:#e6f1f5;\n  padding:16px 18px;\n  border-radius:8px;\n  border:1px solid #0c1a20;\n  overflow-x:auto;\n  line-height:1.6;\n  font-size:14px;\n  margin:1.4em 0;\n  -webkit-overflow-scrolling:touch;\n}\n.qol-article pre code{\n  background:transparent;\n  color:inherit;\n  padding:0;\n  border:0;\n  font-family:\"SFMono-Regular\",Consolas,\"Liberation Mono\",Menlo,monospace;\n  white-space:pre;\n  word-break:normal;\n}\n.qol-article :not(pre) > code{\n  background:#eef2f5;\n  color:#20232a;\n  padding:.15em .4em;\n  border-radius:4px;\n  font-size:.92em;\n  font-family:\"SFMono-Regular\",Consolas,\"Liberation Mono\",Menlo,monospace;\n}\n.qol-article h2{margin-top:1.8em;}\n.qol-article h3{margin-top:1.5em;}\n.qol-article figure{overflow-x:auto;}\n<\/style>\n<div class=\"qol-article\">\n<h2>\u6982\u8981<\/h2>\n<p>React 19 \u306f 2024 \u5e74 12 \u6708\u306b\u5b89\u5b9a\u7248\u304c\u30ea\u30ea\u30fc\u30b9\u3055\u308c\u305f\u30e1\u30b8\u30e3\u30fc\u30d0\u30fc\u30b8\u30e7\u30f3\u3067\u3059\u3002\u30d5\u30a9\u30fc\u30e0\u51e6\u7406\u307e\u308f\u308a\u3092\u5927\u304d\u304f\u5909\u3048\u308b\u300cActions\u300d\u3001\u975e\u540c\u671f\u51e6\u7406\u3092\u30b7\u30f3\u30d7\u30eb\u306b\u6271\u3046 <code>use<\/code> API\u3001<code>forwardRef<\/code> \u3092\u4e0d\u8981\u306b\u3059\u308b ref \u306e\u6271\u3044\u306e\u5909\u66f4\u306a\u3069\u3001\u65e5\u3005\u306e\u5b9f\u88c5\u306b\u52b9\u304f\u5909\u66f4\u304c\u591a\u304f\u5165\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n<p>\u3053\u306e\u8a18\u4e8b\u3067\u306f\u300c\u307e\u305a\u4f55\u304c\u5909\u308f\u3063\u305f\u306e\u304b\u300d\u3092\u5165\u9580\u8005\u5411\u3051\u306b\u6574\u7406\u3057\u307e\u3059\u3002\u500b\u5225 API \u306e\u7d30\u304b\u3044\u4ed5\u69d8\u306f\u516c\u5f0f\u30c9\u30ad\u30e5\u30e1\u30f3\u30c8\u306b\u8b72\u308a\u3001\u5168\u4f53\u50cf\u3092\u3064\u304b\u3080\u3053\u3068\u3092\u76ee\u7684\u306b\u3057\u307e\u3059\u3002<\/p>\n<figure style=\"margin:2em 0;text-align:center;\">\n<svg viewBox=\"0 0 720 360\" width=\"100%\" style=\"max-width:720px;height:auto;font-family:sans-serif;\" role=\"img\" aria-label=\"React 19 \u306e\u65b0\u6a5f\u80fd\u30de\u30c3\u30d7\">\n<rect x=\"0\" y=\"0\" width=\"720\" height=\"360\" fill=\"#f7f9fc\"\/>\n<rect x=\"270\" y=\"18\" width=\"180\" height=\"46\" rx=\"8\" fill=\"#087ea4\"\/>\n<text x=\"360\" y=\"47\" text-anchor=\"middle\" fill=\"#fff\" font-size=\"20\" font-weight=\"bold\">React 19<\/text>\n<!-- 3\u30ab\u30c6\u30b4\u30ea -->\n<rect x=\"30\"  y=\"120\" width=\"200\" height=\"40\" rx=\"6\" fill=\"#20a4c4\"\/>\n<text x=\"130\" y=\"145\" text-anchor=\"middle\" fill=\"#fff\" font-size=\"15\" font-weight=\"bold\">\u30d5\u30a9\u30fc\u30e0 \/ \u975e\u540c\u671f<\/text>\n<rect x=\"260\" y=\"120\" width=\"200\" height=\"40\" rx=\"6\" fill=\"#20a4c4\"\/>\n<text x=\"360\" y=\"145\" text-anchor=\"middle\" fill=\"#fff\" font-size=\"15\" font-weight=\"bold\">\u30c7\u30fc\u30bf\u8aad\u307f\u53d6\u308a<\/text>\n<rect x=\"490\" y=\"120\" width=\"200\" height=\"40\" rx=\"6\" fill=\"#20a4c4\"\/>\n<text x=\"590\" y=\"145\" text-anchor=\"middle\" fill=\"#fff\" font-size=\"15\" font-weight=\"bold\">DX \/ \u30e1\u30bf\u7ba1\u7406<\/text>\n<!-- \u63a5\u7d9a\u7dda -->\n<path d=\"M360 64 L360 100 M130 100 L130 120 M360 100 L360 120 M590 100 L590 120 M130 100 L590 100\" stroke=\"#087ea4\" stroke-width=\"2\" fill=\"none\"\/>\n<!-- \u9805\u76ee -->\n<g font-size=\"13\" fill=\"#1c2b33\">\n<rect x=\"30\"  y=\"176\" width=\"200\" height=\"150\" rx=\"6\" fill=\"#fff\" stroke=\"#cfe3ea\"\/>\n<text x=\"45\" y=\"200\">Actions (useTransition)<\/text>\n<text x=\"45\" y=\"224\">useActionState<\/text>\n<text x=\"45\" y=\"248\">useFormStatus<\/text>\n<text x=\"45\" y=\"272\">useOptimistic<\/text>\n<rect x=\"260\" y=\"176\" width=\"200\" height=\"150\" rx=\"6\" fill=\"#fff\" stroke=\"#cfe3ea\"\/>\n<text x=\"275\" y=\"200\">use(promise)<\/text>\n<text x=\"275\" y=\"224\">use(context)<\/text>\n<text x=\"275\" y=\"248\" fill=\"#6b7c85\" font-size=\"12\">\u203b \u6761\u4ef6\u5206\u5c90\u5185\u3067\u3082\u547c\u3079\u308b<\/text>\n<rect x=\"490\" y=\"176\" width=\"200\" height=\"150\" rx=\"6\" fill=\"#fff\" stroke=\"#cfe3ea\"\/>\n<text x=\"505\" y=\"200\">ref \u3092 props \u3067\u53d7\u53d6<\/text>\n<text x=\"505\" y=\"224\">ref \u30af\u30ea\u30fc\u30f3\u30a2\u30c3\u30d7<\/text>\n<text x=\"505\" y=\"248\">&lt;title&gt;\/&lt;meta&gt; \u81ea\u52d5head<\/text>\n<text x=\"505\" y=\"272\">preload \/ preinit<\/text>\n<text x=\"505\" y=\"296\">&lt;Context&gt; \u3092\u76f4\u63a5\u4f7f\u7528<\/text>\n<\/g>\n<\/svg><figcaption style=\"font-size:13px;color:#6b7c85;margin-top:6px;\">\u56f31: React 19 \u306e\u65b0\u6a5f\u80fd\u30de\u30c3\u30d7\uff08\u672c\u8a18\u4e8b\u3067\u6271\u3046\u7bc4\u56f2\uff09<\/figcaption><\/figure>\n<h2>\u74b0\u5883<\/h2>\n<ul>\n<li>React 19\uff08\u5b89\u5b9a\u7248\uff09<\/li>\n<li>\u8a18\u8f09\u306e\u30b3\u30fc\u30c9\u306f\u6982\u5ff5\u3092\u793a\u3059\u305f\u3081\u306e\u6700\u5c0f\u4f8b\u3067\u3059<\/li>\n<\/ul>\n<h2>\u4e3b\u306a\u65b0\u6a5f\u80fd<\/h2>\n<figure style=\"margin:2em 0;text-align:center;\">\n<svg viewBox=\"0 0 720 210\" width=\"100%\" style=\"max-width:720px;height:auto;font-family:sans-serif;\" role=\"img\" aria-label=\"React 19 Actions \u306e\u30d5\u30a9\u30fc\u30e0\u51e6\u7406\u30d5\u30ed\u30fc\">\n<rect x=\"0\" y=\"0\" width=\"720\" height=\"210\" fill=\"#f7f9fc\"\/>\n<defs><marker id=\"ar\" markerWidth=\"10\" markerHeight=\"10\" refX=\"8\" refY=\"3\" orient=\"auto\"><path d=\"M0,0 L8,3 L0,6 Z\" fill=\"#087ea4\"\/><\/marker><\/defs>\n<g font-size=\"13\" fill=\"#1c2b33\" text-anchor=\"middle\">\n<rect x=\"20\"  y=\"80\" width=\"120\" height=\"50\" rx=\"6\" fill=\"#fff\" stroke=\"#087ea4\"\/>\n<text x=\"80\" y=\"102\">\u9001\u4fe1<\/text><text x=\"80\" y=\"120\" font-size=\"11\" fill=\"#6b7c85\">form action<\/text>\n<rect x=\"180\" y=\"80\" width=\"140\" height=\"50\" rx=\"6\" fill=\"#e6f4f9\" stroke=\"#087ea4\"\/>\n<text x=\"250\" y=\"102\">useActionState<\/text><text x=\"250\" y=\"120\" font-size=\"11\" fill=\"#6b7c85\">isPending=true<\/text>\n<rect x=\"360\" y=\"20\" width=\"150\" height=\"46\" rx=\"6\" fill=\"#fff\" stroke=\"#20a4c4\"\/>\n<text x=\"435\" y=\"42\">useOptimistic<\/text><text x=\"435\" y=\"59\" font-size=\"11\" fill=\"#6b7c85\">UI\u3092\u5148\u306b\u66f4\u65b0<\/text>\n<rect x=\"360\" y=\"140\" width=\"150\" height=\"46\" rx=\"6\" fill=\"#fff\" stroke=\"#20a4c4\"\/>\n<text x=\"435\" y=\"162\">\u30b5\u30fc\u30d0\u30fc\u51e6\u7406<\/text><text x=\"435\" y=\"179\" font-size=\"11\" fill=\"#6b7c85\">await submit()<\/text>\n<rect x=\"560\" y=\"80\" width=\"140\" height=\"50\" rx=\"6\" fill=\"#e6f4f9\" stroke=\"#087ea4\"\/>\n<text x=\"630\" y=\"102\">\u7d50\u679c\u3092 state \u3078<\/text><text x=\"630\" y=\"120\" font-size=\"11\" fill=\"#6b7c85\">isPending=false<\/text>\n<\/g>\n<path d=\"M140 105 L176 105\" stroke=\"#087ea4\" stroke-width=\"2\" marker-end=\"url(#ar)\"\/>\n<path d=\"M320 95 L356 55\" stroke=\"#20a4c4\" stroke-width=\"2\" marker-end=\"url(#ar)\"\/>\n<path d=\"M320 115 L356 160\" stroke=\"#20a4c4\" stroke-width=\"2\" marker-end=\"url(#ar)\"\/>\n<path d=\"M510 160 L556 120\" stroke=\"#087ea4\" stroke-width=\"2\" marker-end=\"url(#ar)\"\/>\n<\/svg><figcaption style=\"font-size:13px;color:#6b7c85;margin-top:6px;\">\u56f32: Actions \u3092\u4f7f\u3063\u305f\u30d5\u30a9\u30fc\u30e0\u51e6\u7406\u306e\u6d41\u308c\uff08\u4fdd\u7559\u72b6\u614b\u30fb\u697d\u89b3\u7684\u66f4\u65b0\u304c\u81ea\u52d5\u5316\u3055\u308c\u308b\uff09<\/figcaption><\/figure>\n<h3>1. Actions\uff08\u975e\u540c\u671f\u51e6\u7406\u3068\u72b6\u614b\u7ba1\u7406\u306e\u7d71\u5408\uff09<\/h3>\n<p>React 19 \u3067\u306f\u3001\u975e\u540c\u671f\u51e6\u7406\u3092 <code>useTransition<\/code> \u306e\u4e2d\u3067\u6271\u3048\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u305f\u3002\u5f93\u6765\u306f\u300c\u4fdd\u7559\u4e2d\u30d5\u30e9\u30b0\u300d\u300c\u30a8\u30e9\u30fc\u300d\u300c\u697d\u89b3\u7684\u66f4\u65b0\u300d\u3092\u81ea\u524d\u306e <code>useState<\/code> \u3067\u7ba1\u7406\u3057\u304c\u3061\u3067\u3057\u305f\u304c\u3001Actions \u3092\u4f7f\u3046\u3068\u3053\u306e\u5b9a\u578b\u51e6\u7406\u3092\u6e1b\u3089\u305b\u307e\u3059\u3002<\/p>\n<pre><code class=\"language-jsx\">import { useTransition } from &quot;react&quot;;\r\n\r\nfunction UpdateName() {\r\n  const [isPending, startTransition] = useTransition();\r\n\r\n  const onSubmit = () =&gt; {\r\n    startTransition(async () =&gt; {\r\n      const error = await updateName(name);\r\n      if (error) {\r\n        \/\/ \u30a8\u30e9\u30fc\u51e6\u7406\r\n        return;\r\n      }\r\n      \/\/ \u6210\u529f\u6642\u306e\u9077\u79fb\u306a\u3069\r\n    });\r\n  };\r\n\r\n  return &lt;button onClick={onSubmit} disabled={isPending}&gt;\u66f4\u65b0&lt;\/button&gt;;\r\n}<\/code><\/pre>\n<p><code>startTransition<\/code> \u306b\u6e21\u3059\u95a2\u6570\u304c\u975e\u540c\u671f\u3067\u3082\u826f\u304f\u306a\u3063\u305f\u70b9\u304c\u30dd\u30a4\u30f3\u30c8\u3067\u3059\u3002\u51e6\u7406\u4e2d\u306f <code>isPending<\/code> \u304c\u81ea\u52d5\u3067 <code>true<\/code> \u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<h3>2. useActionState<\/h3>\n<p>\u30d5\u30a9\u30fc\u30e0\u9001\u4fe1\u306a\u3069\u306e\u300c\u30a2\u30af\u30b7\u30e7\u30f3\u306e\u7d50\u679c\u300d\u3092\u72b6\u614b\u3068\u3057\u3066\u6271\u3046\u305f\u3081\u306e\u30d5\u30c3\u30af\u3067\u3059\u3002\u9001\u4fe1\u95a2\u6570\u30fb\u4fdd\u7559\u72b6\u614b\u30fb\u76f4\u8fd1\u306e\u7d50\u679c\u3092\u307e\u3068\u3081\u3066\u7ba1\u7406\u3067\u304d\u307e\u3059\u3002<\/p>\n<pre><code class=\"language-jsx\">import { useActionState } from &quot;react&quot;;\r\n\r\nfunction Form() {\r\n  const [state, formAction, isPending] = useActionState(\r\n    async (prevState, formData) =&gt; {\r\n      const error = await submit(formData);\r\n      return error ?? &quot;ok&quot;;\r\n    },\r\n    null\r\n  );\r\n\r\n  return (\r\n    &lt;form action={formAction}&gt;\r\n      &lt;input name=&quot;email&quot; \/&gt;\r\n      &lt;button disabled={isPending}&gt;\u9001\u4fe1&lt;\/button&gt;\r\n      {state &amp;&amp; &lt;p&gt;{state}&lt;\/p&gt;}\r\n    &lt;\/form&gt;\r\n  );\r\n}<\/code><\/pre>\n<p><code>&lt;form action={...}&gt;<\/code> \u306b\u95a2\u6570\u3092\u76f4\u63a5\u6e21\u305b\u308b\u3088\u3046\u306b\u306a\u3063\u305f\u306e\u3082 19 \u3067\u306e\u5909\u66f4\u70b9\u3067\u3059\u3002<\/p>\n<h3>3. useFormStatus<\/h3>\n<p>\u30d5\u30a9\u30fc\u30e0\u306e\u9001\u4fe1\u72b6\u614b\u3092\u3001\u89aa\u304b\u3089\u30d7\u30ed\u30c3\u30d7\u30b9\u3092\u6e21\u3055\u305a\u306b\u5b50\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u304b\u3089\u53c2\u7167\u3067\u304d\u308b\u30d5\u30c3\u30af\u3067\u3059\u3002\u9001\u4fe1\u30dc\u30bf\u30f3\u3092\u5171\u901a\u90e8\u54c1\u5316\u3057\u305f\u3044\u3068\u304d\u306b\u4fbf\u5229\u3067\u3059\u3002<\/p>\n<pre><code class=\"language-jsx\">import { useFormStatus } from &quot;react-dom&quot;;\r\n\r\nfunction SubmitButton() {\r\n  const { pending } = useFormStatus();\r\n  return &lt;button disabled={pending}&gt;\u9001\u4fe1&lt;\/button&gt;;\r\n}<\/code><\/pre>\n<h3>4. useOptimistic<\/h3>\n<p>\u30b5\u30fc\u30d0\u30fc\u5fdc\u7b54\u3092\u5f85\u3064\u9593\u3001UI \u3092\u5148\u306b\u66f4\u65b0\u3057\u3066\u304a\u304f\u300c\u697d\u89b3\u7684\u66f4\u65b0\u300d\u3092\u6271\u3046\u30d5\u30c3\u30af\u3067\u3059\u3002\u5fdc\u7b54\u304c\u78ba\u5b9a\u3059\u308b\u3068\u81ea\u52d5\u7684\u306b\u5b9f\u969b\u306e\u5024\u3078\u623b\u308a\u307e\u3059\u3002<\/p>\n<pre><code class=\"language-jsx\">import { useOptimistic } from &quot;react&quot;;\r\n\r\nfunction Thread({ messages, sendMessage }) {\r\n  const [optimisticMessages, addOptimistic] = useOptimistic(\r\n    messages,\r\n    (state, newMessage) =&gt; [...state, { text: newMessage, sending: true }]\r\n  );\r\n  \/\/ \u30d5\u30a9\u30fc\u30e0\u9001\u4fe1\u6642\u306b addOptimistic \u3092\u547c\u3076\r\n}<\/code><\/pre>\n<h3>5. use API<\/h3>\n<p>Promise \u3084\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092\u8aad\u307f\u53d6\u308b\u65b0\u3057\u3044 API \u3067\u3059\u3002<code>use<\/code> \u306f\u6761\u4ef6\u5206\u5c90\u3084\u30eb\u30fc\u30d7\u306e\u4e2d\u3067\u3082\u547c\u3079\u308b\u305f\u3081\u3001\u3053\u308c\u307e\u3067\u306e\u30d5\u30c3\u30af\u306e\u30eb\u30fc\u30eb\u3088\u308a\u67d4\u8edf\u306b\u4f7f\u3048\u307e\u3059\u3002Promise \u3092\u6e21\u3059\u3068\u3001\u89e3\u6c7a\u3059\u308b\u307e\u3067\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u304c\u30b5\u30b9\u30da\u30f3\u30c9\u3057\u307e\u3059\u3002<\/p>\n<pre><code class=\"language-jsx\">import { use } from &quot;react&quot;;\r\n\r\nfunction Comments({ commentsPromise }) {\r\n  const comments = use(commentsPromise); \/\/ \u89e3\u6c7a\u307e\u3067\u30b5\u30b9\u30da\u30f3\u30c9\r\n  return comments.map((c) =&gt; &lt;p key={c.id}&gt;{c.text}&lt;\/p&gt;);\r\n}<\/code><\/pre>\n<p>\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u306e\u8aad\u307f\u53d6\u308a\u306b\u3082\u4f7f\u3048\u307e\u3059\u3002<\/p>\n<pre><code class=\"language-jsx\">const theme = use(ThemeContext);<\/code><\/pre>\n<h3>6. ref \u3092\u30d7\u30ed\u30c3\u30d7\u30b9\u3068\u3057\u3066\u53d7\u3051\u53d6\u308c\u308b<\/h3>\n<p>\u95a2\u6570\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u304c <code>ref<\/code> \u3092\u901a\u5e38\u306e\u30d7\u30ed\u30c3\u30d7\u30b9\u3068\u3057\u3066\u53d7\u3051\u53d6\u308c\u308b\u3088\u3046\u306b\u306a\u308a\u3001\u591a\u304f\u306e\u30b1\u30fc\u30b9\u3067 <code>forwardRef<\/code> \u304c\u4e0d\u8981\u306b\u306a\u308a\u307e\u3057\u305f\u3002<\/p>\n<pre><code class=\"language-jsx\">function MyInput({ placeholder, ref }) {\r\n  return &lt;input placeholder={placeholder} ref={ref} \/&gt;;\r\n}\r\n\r\n\/\/ \u4f7f\u3046\u5074\r\n&lt;MyInput ref={inputRef} placeholder=&quot;\u540d\u524d&quot; \/&gt;<\/code><\/pre>\n<h3>7. ref \u306e\u30af\u30ea\u30fc\u30f3\u30a2\u30c3\u30d7\u95a2\u6570<\/h3>\n<p><code>ref<\/code> \u30b3\u30fc\u30eb\u30d0\u30c3\u30af\u304b\u3089\u30af\u30ea\u30fc\u30f3\u30a2\u30c3\u30d7\u95a2\u6570\u3092\u8fd4\u305b\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u305f\u3002\u8981\u7d20\u304c\u30a2\u30f3\u30de\u30a6\u30f3\u30c8\u3055\u308c\u308b\u969b\u306b\u547c\u3070\u308c\u307e\u3059\u3002<\/p>\n<pre><code class=\"language-jsx\">&lt;input\r\n  ref={(node) =&gt; {\r\n    \/\/ \u30bb\u30c3\u30c8\u30a2\u30c3\u30d7\r\n    return () =&gt; {\r\n      \/\/ \u30af\u30ea\u30fc\u30f3\u30a2\u30c3\u30d7\r\n    };\r\n  }}\r\n\/&gt;<\/code><\/pre>\n<h3>8. \u30c9\u30ad\u30e5\u30e1\u30f3\u30c8\u30e1\u30bf\u30c7\u30fc\u30bf\u306e\u30b5\u30dd\u30fc\u30c8<\/h3>\n<p>\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u5185\u306b\u66f8\u3044\u305f <code>&lt;title&gt;<\/code> \/ <code>&lt;meta&gt;<\/code> \/ <code>&lt;link&gt;<\/code> \u304c\u81ea\u52d5\u7684\u306b <code>&lt;head&gt;<\/code> \u3078\u5f15\u304d\u4e0a\u3052\u3089\u308c\u307e\u3059\u3002SEO \u307e\u308f\u308a\u306e\u30bf\u30b0\u7ba1\u7406\u304c\u7d20\u76f4\u306b\u66f8\u3051\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u305f\u3002<\/p>\n<pre><code class=\"language-jsx\">function Article({ post }) {\r\n  return (\r\n    &lt;article&gt;\r\n      &lt;title&gt;{post.title}&lt;\/title&gt;\r\n      &lt;meta name=&quot;description&quot; content={post.summary} \/&gt;\r\n      &lt;h1&gt;{post.title}&lt;\/h1&gt;\r\n    &lt;\/article&gt;\r\n  );\r\n}<\/code><\/pre>\n<h3>9. \u30b9\u30bf\u30a4\u30eb\u30b7\u30fc\u30c8\u30fb\u30b9\u30af\u30ea\u30d7\u30c8\u30fb\u30ea\u30bd\u30fc\u30b9\u306e\u30d7\u30ea\u30ed\u30fc\u30c9<\/h3>\n<p>\u30b9\u30bf\u30a4\u30eb\u30b7\u30fc\u30c8\u306b\u8aad\u307f\u8fbc\u307f\u512a\u5148\u5ea6\uff08precedence\uff09\u3092\u6307\u5b9a\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u3001\u975e\u540c\u671f\u30b9\u30af\u30ea\u30d7\u30c8\u306e\u91cd\u8907\u8aad\u307f\u8fbc\u307f\u3082 React \u5074\u3067\u7ba1\u7406\u3055\u308c\u307e\u3059\u3002\u3042\u308f\u305b\u3066 <code>preload<\/code> \/ <code>preinit<\/code> \/ <code>prefetchDNS<\/code> \/ <code>preconnect<\/code> \u3068\u3044\u3063\u305f\u30ea\u30bd\u30fc\u30b9\u5148\u8aad\u307f\u7528\u306e API \u304c\u8ffd\u52a0\u3055\u308c\u307e\u3057\u305f\u3002<\/p>\n<pre><code class=\"language-jsx\">import { preload, preinit } from &quot;react-dom&quot;;\r\n\r\npreload(&quot;\/fonts\/main.woff2&quot;, { as: &quot;font&quot; });\r\npreinit(&quot;\/script.js&quot;, { as: &quot;script&quot; });<\/code><\/pre>\n<h3>10. Context \u3092\u76f4\u63a5\u30d7\u30ed\u30d0\u30a4\u30c0\u30fc\u3068\u3057\u3066\u4f7f\u3048\u308b<\/h3>\n<p><code>&lt;Context.Provider&gt;<\/code> \u306e\u4ee3\u308f\u308a\u306b <code>&lt;Context&gt;<\/code> \u3092\u305d\u306e\u307e\u307e\u66f8\u3051\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u305f\u3002<\/p>\n<pre><code class=\"language-jsx\">const ThemeContext = createContext(&quot;&quot;);\r\n\r\nfunction App({ children }) {\r\n  return &lt;ThemeContext value=&quot;dark&quot;&gt;{children}&lt;\/ThemeContext&gt;;\r\n}<\/code><\/pre>\n<p><code>&lt;Context.Provider&gt;<\/code> \u3082\u5f15\u304d\u7d9a\u304d\u4f7f\u3048\u307e\u3059\u304c\u3001\u5c06\u6765\u7684\u306b\u306f\u975e\u63a8\u5968\u306b\u306a\u308b\u4e88\u5b9a\u3068\u3055\u308c\u3066\u3044\u307e\u3059\u3002<\/p>\n<h2>\u78ba\u8a8d\u65b9\u6cd5<\/h2>\n<ul>\n<li>\u65e2\u5b58\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3092 19 \u306b\u4e0a\u3052\u308b\u5834\u5408\u306f\u3001\u307e\u305a\u516c\u5f0f\u306e\u30a2\u30c3\u30d7\u30b0\u30ec\u30fc\u30c9\u30ac\u30a4\u30c9\u306b\u6cbf\u3063\u3066\u79fb\u884c\u3057\u307e\u3059<\/li>\n<li><code>forwardRef<\/code> \u3084 <code>&lt;Context.Provider&gt;<\/code> \u306f\u5f53\u9762\u52d5\u4f5c\u3057\u307e\u3059\u304c\u3001\u9806\u6b21\u65b0\u3057\u3044\u66f8\u304d\u65b9\u3078\u5bc4\u305b\u3066\u3044\u304f\u3068\u4fdd\u5b88\u304c\u697d\u306b\u306a\u308a\u307e\u3059<\/li>\n<li>Actions \u7cfb\u306e\u30d5\u30c3\u30af\uff08<code>useActionState<\/code> \/ <code>useFormStatus<\/code> \/ <code>useOptimistic<\/code>\uff09\u306f\u30d5\u30a9\u30fc\u30e0\u4e2d\u5fc3\u306e\u753b\u9762\u304b\u3089\u8a66\u3059\u3068\u52b9\u679c\u3092\u5b9f\u611f\u3057\u3084\u3059\u3044\u3067\u3059<\/li>\n<\/ul>\n<h2>\u6ce8\u610f\u70b9<\/h2>\n<ul>\n<li>\u3053\u3053\u3067\u6319\u3052\u305f\u6319\u52d5\u306f\u30d0\u30fc\u30b8\u30e7\u30f3\u3084\u5229\u7528\u3057\u3066\u3044\u308b\u30d5\u30ec\u30fc\u30e0\u30ef\u30fc\u30af\uff08\u4f8b: Next.js \u306a\u3069\u306e\u30e1\u30bf\u30d5\u30ec\u30fc\u30e0\u30ef\u30fc\u30af\uff09\u306b\u3088\u3063\u3066\u63a8\u5968\u306e\u4f7f\u3044\u65b9\u304c\u7570\u306a\u308b\u5834\u5408\u304c\u3042\u308a\u307e\u3059\u3002\u6700\u65b0\u306e\u516c\u5f0f\u30c9\u30ad\u30e5\u30e1\u30f3\u30c8\u3092\u4e00\u6b21\u60c5\u5831\u3068\u3057\u3066\u78ba\u8a8d\u3057\u3066\u304f\u3060\u3055\u3044<\/li>\n<li>\u697d\u89b3\u7684\u66f4\u65b0\u3084\u30b5\u30b9\u30da\u30f3\u30c9\u3092\u4f34\u3046 API \u306f\u3001\u30a8\u30e9\u30fc\u6642\u306e\u30d5\u30a9\u30fc\u30eb\u30d0\u30c3\u30af\u8a2d\u8a08\uff08Error Boundary \/ Suspense \u306e <code>fallback<\/code>\uff09\u3068\u30bb\u30c3\u30c8\u3067\u8003\u3048\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059<\/li>\n<\/ul>\n<h2>\u307e\u3068\u3081<\/h2>\n<p>React 19 \u306f\u300c\u975e\u540c\u671f\u30fb\u30d5\u30a9\u30fc\u30e0\u51e6\u7406\u306e\u5b9a\u578b\u30b3\u30fc\u30c9\u3092\u6e1b\u3089\u3059\u300d\u65b9\u5411\u306e\u5909\u66f4\u304c\u4e2d\u5fc3\u3067\u3059\u3002<\/p>\n<ul>\n<li>Actions \u3068 <code>useActionState<\/code> \/ <code>useFormStatus<\/code> \/ <code>useOptimistic<\/code> \u3067\u30d5\u30a9\u30fc\u30e0\u51e6\u7406\u304c\u7c21\u6f54\u306b<\/li>\n<li><code>use<\/code> \u3067 Promise\u30fb\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092\u67d4\u8edf\u306b\u8aad\u307f\u53d6\u308a<\/li>\n<li><code>ref<\/code> \u304c\u30d7\u30ed\u30c3\u30d7\u30b9\u5316\u3057 <code>forwardRef<\/code> \u304c\u4e0d\u8981\u306b<\/li>\n<li>\u30e1\u30bf\u30c7\u30fc\u30bf\u30fb\u30b9\u30bf\u30a4\u30eb\u30fb\u30ea\u30bd\u30fc\u30b9\u5148\u8aad\u307f\u306e\u30b5\u30dd\u30fc\u30c8\u5f37\u5316<\/li>\n<\/ul>\n<p>\u307e\u305a\u306f\u65b0\u898f\u753b\u9762\u3084\u5c0f\u3055\u306a\u30d5\u30a9\u30fc\u30e0\u304b\u3089\u65b0 API \u3092\u8a66\u3057\u3001\u5f90\u3005\u306b\u65e2\u5b58\u30b3\u30fc\u30c9\u3092\u5bc4\u305b\u3066\u3044\u304f\u306e\u304c\u304a\u3059\u3059\u3081\u3067\u3059\u3002<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>React 19 \u3067\u8ffd\u52a0\u3055\u308c\u305f Actions\u30fbuse\u30fbServer Components \u306a\u3069\u306e\u65b0\u6a5f\u80fd\u3092\u3001\u5165\u9580\u8005\u5411\u3051\u306b\u8981\u70b9\u3060\u3051\u307e\u3068\u3081\u307e\u3057\u305f\u3002<\/p>\n","protected":false},"author":1,"featured_media":3371,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"sns_share_botton_hide":"","vkExUnit_sns_title":"","_vk_print_noindex":"","sitemap_hide":"","_veu_custom_css":"","veu_display_promotion_alert":"common","vkexunit_cta_each_option":"","_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[36],"tags":[365,1161,970,1162],"class_list":["post-3247","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-javascript-memorandum","tag-javascript","tag-react","tag-970","tag-1162"],"veu_head_title_object":{"title":"","add_site_title":""},"jetpack_publicize_connections":[],"jetpack-related-posts":[],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"https:\/\/qol-kk.com\/wp2\/wp-content\/uploads\/2026\/09\/image_995b29ff.jpg","_links":{"self":[{"href":"https:\/\/qol-kk.com\/wp2\/wp-json\/wp\/v2\/posts\/3247","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/qol-kk.com\/wp2\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/qol-kk.com\/wp2\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/qol-kk.com\/wp2\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/qol-kk.com\/wp2\/wp-json\/wp\/v2\/comments?post=3247"}],"version-history":[{"count":1,"href":"https:\/\/qol-kk.com\/wp2\/wp-json\/wp\/v2\/posts\/3247\/revisions"}],"predecessor-version":[{"id":3276,"href":"https:\/\/qol-kk.com\/wp2\/wp-json\/wp\/v2\/posts\/3247\/revisions\/3276"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/qol-kk.com\/wp2\/wp-json\/wp\/v2\/media\/3371"}],"wp:attachment":[{"href":"https:\/\/qol-kk.com\/wp2\/wp-json\/wp\/v2\/media?parent=3247"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/qol-kk.com\/wp2\/wp-json\/wp\/v2\/categories?post=3247"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/qol-kk.com\/wp2\/wp-json\/wp\/v2\/tags?post=3247"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}