[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"verticals":3,"playground-react-weekly-useeffectevent-stale-closures":44,"search-suggestions":58},[4,20,32],{"id":5,"slug":6,"name":7,"tagline":8,"description":9,"accentFrom":10,"accentTo":11,"icon":12,"defaultLocale":13,"locales":14,"features":16,"position":19},"019fe637-3d33-714b-b57f-23e163ffca0c","dev","Web Development","Read it. Run it. Prove it.","A post a day on modern web development — most with an editable playground and a quiz that explains every answer. Free, no account needed.","violet-500","cyan-400","◇","en",[13,15],"fa",{"courses":17,"paths":17,"articles":17,"exams":18,"flashcards":18,"packages":17,"community":17,"certificates":17,"teams":17,"commerce":17},true,false,0,{"id":21,"slug":22,"name":23,"tagline":24,"description":25,"accentFrom":26,"accentTo":10,"icon":27,"defaultLocale":13,"locales":28,"features":30,"position":31},"019fe637-3dc2-754c-8657-0f175bfee7c6","lang","Languages","Learn a language the way you learn a codebase.","Grammar explained the way good documentation explains an API — one idea at a time, each with a quiz.","amber-400","⌘",[13,15,29],"es",{"courses":18,"paths":18,"articles":17,"exams":18,"flashcards":17,"packages":18,"community":17,"certificates":17,"teams":18,"commerce":18},2,{"id":33,"slug":34,"name":35,"tagline":36,"description":37,"accentFrom":38,"accentTo":39,"icon":40,"defaultLocale":13,"locales":41,"features":42,"position":43},"7b3c16f2-931d-410e-802e-e1fa4edab7de","soft","Soft Skills","The half of the job nobody wrote documentation for.","Weekly, on the parts of working life that decide more than your code does — first weeks, meetings, interviews, promotions, and the people around you. Written from what actually happens, and recorded as a podcast you can listen to on the walk.","emerald-400","teal-300","◉",[13],{"courses":18,"paths":18,"articles":17,"exams":18,"flashcards":18,"packages":18,"community":17,"certificates":18,"teams":18,"commerce":18},3,{"slug":45,"title":46,"summary":47,"html":48,"css":49,"js":50,"config":51,"doc":53},"react-weekly-useeffectevent-stale-closures","useEffectEvent vs the deps array — interactive playground",null,"\u003Cdiv class=\"pg\">\n    \u003Ch1 class=\"pg-title\">🎮 useEffectEvent vs. the dependency array\u003C\u002Fh1>\n    \u003Cp class=\"pg-sub\">\n      Same chat room, three real \u003Ccode>useEffect\u003C\u002Fcode> strategies. Toggle the room and the theme,\n      then press \u003Cb>Send test notification\u003C\u002Fb> and watch what each strategy reports.\n    \u003C\u002Fp>\n\n    \u003Cdiv class=\"banner info show\" id=\"boot\">Loading the real React 19.3.0 runtime from the CDN…\u003C\u002Fdiv>\n\n    \u003Cdiv id=\"app\" hidden>\n      \u003Cdiv class=\"panel\">\n        \u003Cdiv class=\"panel-label\">\u003Cspan class=\"n\">1\u003C\u002Fspan> Pick the Effect strategy\u003C\u002Fdiv>\n        \u003Cdiv class=\"seg\" id=\"strategySeg\" role=\"radiogroup\">\n          \u003Cbutton class=\"seg-btn\" data-strategy=\"deps\" aria-pressed=\"true\">A) theme in deps\u003C\u002Fbutton>\n          \u003Cbutton class=\"seg-btn\" data-strategy=\"stale\" aria-pressed=\"false\">B) theme omitted (stale)\u003C\u002Fbutton>\n          \u003Cbutton class=\"seg-btn\" data-strategy=\"event\" aria-pressed=\"false\">C) useEffectEvent\u003C\u002Fbutton>\n        \u003C\u002Fdiv>\n        \u003Cp class=\"strategy-note\" id=\"strategyNote\">\u003C\u002Fp>\n      \u003C\u002Fdiv>\n\n      \u003Cdiv class=\"panel\" style=\"margin-top:16px\">\n        \u003Cdiv class=\"panel-label\">\u003Cspan class=\"n\">2\u003C\u002Fspan> Change the room or the theme\u003C\u002Fdiv>\n        \u003Cdiv class=\"btn-row\">\n          \u003Cdiv class=\"seg\" id=\"roomSeg\" role=\"radiogroup\">\n            \u003Cbutton class=\"seg-btn\" data-room=\"general\" aria-pressed=\"true\">#general\u003C\u002Fbutton>\n            \u003Cbutton class=\"seg-btn\" data-room=\"random\" aria-pressed=\"false\">#random\u003C\u002Fbutton>\n          \u003C\u002Fdiv>\n          \u003Clabel class=\"toggle\" style=\"margin-left:10px\">\n            \u003Cinput type=\"checkbox\" id=\"themeToggle\" \u002F>\u003Cspan class=\"switch\">\u003C\u002Fspan>\n            \u003Cspan id=\"themeLabel\">Light theme\u003C\u002Fspan>\n          \u003C\u002Flabel>\n        \u003C\u002Fdiv>\n        \u003Cdiv class=\"btn-row\" style=\"margin-top:12px\">\n          \u003Cbutton class=\"btn primary\" id=\"notifyBtn\">🔔 Send test notification\u003C\u002Fbutton>\n          \u003Cbutton class=\"btn ghost\" id=\"resetBtn\">Reset counters\u003C\u002Fbutton>\n        \u003C\u002Fdiv>\n      \u003C\u002Fdiv>\n\n      \u003Cdiv class=\"panel\" style=\"margin-top:16px\">\n        \u003Cdiv class=\"panel-label\">\u003Cspan class=\"n\">3\u003C\u002Fspan> What actually happened\u003C\u002Fdiv>\n        \u003Cdiv class=\"stat-row\">\n          \u003Cdiv class=\"stat\">\n            \u003Cspan class=\"big-num\" id=\"reconnectCount\">0\u003C\u002Fspan>\n            \u003Cspan class=\"label\">Reconnects since reset\u003C\u002Fspan>\n          \u003C\u002Fdiv>\n          \u003Cdiv class=\"stat\">\n            \u003Cspan class=\"big-num\" id=\"notifyCount\">0\u003C\u002Fspan>\n            \u003Cspan class=\"label\">Notifications sent\u003C\u002Fspan>\n          \u003C\u002Fdiv>\n        \u003C\u002Fdiv>\n        \u003Cdiv class=\"log\" id=\"log\" aria-live=\"polite\" style=\"margin-top:12px\">\u003C\u002Fdiv>\n      \u003C\u002Fdiv>\n    \u003C\u002Fdiv>\n  \u003C\u002Fdiv>","\u002F*\n * Shared playground design system — daily-post\n * ============================================\n * Link it from any post's playground\u002Findex.html (no per-post boilerplate):\n *\n *   \u003Clink rel=\"stylesheet\" href=\"..\u002F..\u002F..\u002Fplayground\u002Fassets\u002Fbase.css\" \u002F>\n *\n * The relative path resolves the same locally (posts\u002F\u003Cbase>\u002Fplayground\u002F) and on\n * the deployed host (public\u002Fposts\u002F\u003Cbase>\u002Fplayground\u002F), because build-site.js\n * mirrors this file to public\u002Fplayground\u002Fassets\u002Fbase.css. For a CodeSandbox\n * --embed, playground.js inlines this file so the single-file sandbox still styles.\n *\n * Then write ONLY the demo-specific CSS in your inline \u003Cstyle>. Everything below\n * — tokens, layout, panels, buttons, toggles, sliders, code blocks, status\u002Flog,\n * banners, presets — comes for free and looks consistent across every post.\n *\n * Theme-aware: dark by default, light via prefers-color-scheme AND a\n * [data-theme] override on \u003Chtml> (so a toggle can force either). Accessible:\n * real focus rings, adequate contrast, reduced-motion honored.\n *\u002F\n\n\u002F* ---------- design tokens ---------- *\u002F\n:root {\n  --bg: #0d1117;\n  --bg-grid: #ffffff0a;\n  --panel: #161b22;\n  --panel-2: #0b0e14;\n  --card: #0b0e14;\n  --ink: #e8ebf2;\n  --muted: #9aa4b2;\n  --faint: #6b7688;\n  --line: #232a35;\n  --line-soft: #ffffff12;\n  --accent: #7c9cff;\n  --accent-ink: #0b0e14;\n  --good: #3fb950;\n  --warn: #f0883e;\n  --bad: #f85149;\n  --info: #58a6ff;\n  --radius: 14px;\n  --radius-sm: 9px;\n  --shadow: 0 8px 30px #0006;\n  --shadow-sm: 0 4px 14px #0005;\n  --mono: ui-monospace, SFMono-Regular, \"SF Mono\", Menlo, Consolas, \"Liberation Mono\", monospace;\n  --sans: ui-sans-serif, system-ui, -apple-system, \"Segoe UI\", Roboto, \"Helvetica Neue\", sans-serif;\n  color-scheme: dark;\n}\n\n\u002F* Light theme — system preference, overridable by [data-theme] on \u003Chtml>. *\u002F\n@media (prefers-color-scheme: light) {\n  :root:not([data-theme=\"dark\"]) {\n    --bg: #f4f6fb;\n    --bg-grid: #00000008;\n    --panel: #ffffff;\n    --panel-2: #f0f3f9;\n    --card: #f7f9fc;\n    --ink: #131722;\n    --muted: #5b6472;\n    --faint: #8a93a3;\n    --line: #e2e7f0;\n    --line-soft: #00000010;\n    --accent: #2f6df0;\n    --accent-ink: #ffffff;\n    --good: #1a7f37;\n    --warn: #bc4c00;\n    --bad: #cf222e;\n    --info: #0969da;\n    --shadow: 0 8px 30px #0000001f;\n    --shadow-sm: 0 4px 14px #00000014;\n    color-scheme: light;\n  }\n}\n:root[data-theme=\"light\"] {\n  --bg: #f4f6fb;\n  --bg-grid: #00000008;\n  --panel: #ffffff;\n  --panel-2: #f0f3f9;\n  --card: #f7f9fc;\n  --ink: #131722;\n  --muted: #5b6472;\n  --faint: #8a93a3;\n  --line: #e2e7f0;\n  --line-soft: #00000010;\n  --accent: #2f6df0;\n  --accent-ink: #ffffff;\n  --good: #1a7f37;\n  --warn: #bc4c00;\n  --bad: #cf222e;\n  --info: #0969da;\n  --shadow: 0 8px 30px #0000001f;\n  --shadow-sm: 0 4px 14px #00000014;\n  color-scheme: light;\n}\n\n\u002F* ---------- reset & base ---------- *\u002F\n*, *::before, *::after { box-sizing: border-box; }\n\nbody {\n  margin: 0;\n  min-height: 100vh;\n  font-family: var(--sans);\n  color: var(--ink);\n  background:\n    radial-gradient(circle at 1px 1px, var(--bg-grid) 1px, transparent 0) 0 0 \u002F 24px 24px,\n    var(--bg);\n  display: flex;\n  justify-content: center;\n  align-items: flex-start;\n  padding: clamp(14px, 3vw, 26px);\n  line-height: 1.55;\n  -webkit-font-smoothing: antialiased;\n  text-rendering: optimizeLegibility;\n}\n\n\u002F* The single content column. *\u002F\n.pg {\n  width: 100%;\n  max-width: 860px;\n}\n\n\u002F* ---------- header ---------- *\u002F\n.pg-title {\n  font-size: clamp(1.15rem, 1rem + 1vw, 1.4rem);\n  font-weight: 800;\n  letter-spacing: -0.02em;\n  margin: 0 0 4px;\n  display: flex;\n  align-items: center;\n  gap: 9px;\n}\n.pg-sub {\n  color: var(--muted);\n  font-size: 0.92rem;\n  line-height: 1.5;\n  margin: 0 0 16px;\n  max-width: 66ch;\n}\n.pg-sub strong, .pg-sub b { color: var(--ink); font-weight: 700; }\n.pg-sub code { font-family: var(--mono); background: var(--line-soft); color: var(--accent);\n  padding: 1px 6px; border-radius: 6px; font-size: 0.85em; }\n\n\u002F* ---------- panels ---------- *\u002F\n.panel {\n  background: var(--panel);\n  border: 1px solid var(--line);\n  border-radius: var(--radius);\n  padding: 16px 18px;\n  margin-bottom: 14px;\n  box-shadow: var(--shadow-sm);\n}\n.panel-label {\n  font-size: 0.7rem;\n  text-transform: uppercase;\n  letter-spacing: 0.08em;\n  color: var(--muted);\n  font-weight: 800;\n  margin: 0 0 13px;\n  display: flex;\n  align-items: center;\n  gap: 8px;\n}\n.panel-label .n {\n  display: inline-grid; place-items: center;\n  width: 18px; height: 18px; border-radius: 50%;\n  background: var(--accent); color: var(--accent-ink);\n  font-size: 0.66rem; font-weight: 800;\n}\n\n\u002F* ---------- layout helpers ---------- *\u002F\n.row { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; }\n.row.between { justify-content: space-between; }\n.col { display: flex; flex-direction: column; gap: 10px; }\n.grow { flex: 1 1 0; min-width: 0; }\n.wrap-controls { display: flex; flex-wrap: wrap; gap: 16px 24px; align-items: flex-end; }\n.field { display: flex; flex-direction: column; gap: 7px; min-width: 0; }\n.field > .label, .ctl-label {\n  font-size: 0.7rem; text-transform: uppercase; letter-spacing: 0.04em;\n  color: var(--muted); font-weight: 800;\n}\n\n\u002F* ---------- buttons ---------- *\u002F\n.btn {\n  font: inherit; font-weight: 650; font-size: 0.88rem;\n  cursor: pointer; user-select: none;\n  border: 1px solid var(--line);\n  background: var(--card); color: var(--ink);\n  padding: 9px 15px; border-radius: var(--radius-sm);\n  display: inline-flex; align-items: center; gap: 8px;\n  transition: background .15s ease, border-color .15s ease, transform .05s ease, color .15s ease;\n}\n.btn:hover { background: var(--line-soft); border-color: var(--muted); }\n.btn:active { transform: translateY(1px); }\n.btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }\n.btn[disabled] { opacity: 0.45; cursor: not-allowed; }\n.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }\n.btn.primary:hover { filter: brightness(1.08); background: var(--accent); }\n.btn.good { background: var(--good); border-color: var(--good); color: #04140a; }\n.btn.bad  { background: var(--bad);  border-color: var(--bad);  color: #fff; }\n.btn.ghost { background: transparent; }\n.btn.sm { padding: 6px 11px; font-size: 0.82rem; }\n\n.btn-row { display: flex; flex-wrap: wrap; gap: 9px; }\n\n\u002F* Segmented control — a row of buttons where one is active (aria-pressed). *\u002F\n.seg { display: inline-flex; background: var(--card); border: 1px solid var(--line);\n  border-radius: var(--radius-sm); padding: 3px; gap: 3px; }\n.seg button {\n  font: inherit; font-weight: 650; font-size: 0.84rem; cursor: pointer;\n  border: none; background: transparent; color: var(--muted);\n  padding: 7px 13px; border-radius: 7px;\n  transition: background .15s ease, color .15s ease;\n}\n.seg button:hover { color: var(--ink); }\n.seg button[aria-pressed=\"true\"] { background: var(--accent); color: var(--accent-ink); }\n.seg button:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }\n\n\u002F* Preset chips — worked-example shortcuts. *\u002F\n.presets { display: flex; flex-wrap: wrap; gap: 8px; }\n.presets .btn { background: var(--panel-2); }\n\n\u002F* ---------- toggle switch ---------- *\u002F\n.toggle { display: inline-flex; align-items: center; gap: 10px; cursor: pointer;\n  font-size: 0.88rem; font-weight: 600; user-select: none; }\n.toggle input { position: absolute; opacity: 0; width: 0; height: 0; }\n.switch { position: relative; width: 44px; height: 25px; border-radius: 999px; flex: none;\n  background: var(--line); border: 1px solid var(--line); transition: background .18s ease; }\n.switch::after { content: \"\"; position: absolute; top: 2px; left: 2px; width: 19px; height: 19px;\n  border-radius: 50%; background: #cfd6e4; transition: transform .18s ease; box-shadow: 0 1px 3px #0006; }\n.toggle input:checked + .switch { background: var(--good); border-color: var(--good); }\n.toggle input:checked + .switch::after { transform: translateX(19px); background: #fff; }\n.toggle input:focus-visible + .switch { outline: 2px solid var(--accent); outline-offset: 2px; }\n\n\u002F* ---------- range slider ---------- *\u002F\ninput[type=\"range\"] {\n  -webkit-appearance: none; appearance: none; width: 100%; height: 6px;\n  background: var(--line); border-radius: 999px; outline: none; cursor: pointer; margin: 8px 0;\n}\ninput[type=\"range\"]::-webkit-slider-thumb {\n  -webkit-appearance: none; appearance: none; width: 19px; height: 19px; border-radius: 50%;\n  background: var(--accent); border: 2px solid var(--panel); box-shadow: var(--shadow-sm); cursor: pointer;\n}\ninput[type=\"range\"]::-moz-range-thumb {\n  width: 19px; height: 19px; border-radius: 50%; background: var(--accent);\n  border: 2px solid var(--panel); box-shadow: var(--shadow-sm); cursor: pointer;\n}\ninput[type=\"range\"]:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }\n\n\u002F* ---------- text inputs \u002F selects ---------- *\u002F\ninput[type=\"text\"], input[type=\"number\"], input[type=\"search\"], select, textarea {\n  font: inherit; color: var(--ink); background: var(--card);\n  border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 8px 11px; width: 100%;\n}\ntextarea { font-family: var(--mono); font-size: 0.85rem; line-height: 1.6; resize: vertical; }\ninput:focus-visible, select:focus-visible, textarea:focus-visible {\n  outline: 2px solid var(--accent); outline-offset: 1px; border-color: var(--accent);\n}\n\n\u002F* ---------- status \u002F output \u002F log ---------- *\u002F\n.status {\n  display: flex; align-items: center; gap: 9px; flex-wrap: wrap;\n  font-size: 0.9rem; font-weight: 600;\n  padding: 11px 14px; border-radius: var(--radius-sm);\n  background: var(--panel-2); border: 1px solid var(--line); color: var(--ink);\n}\n.status.good { border-color: color-mix(in srgb, var(--good) 55%, var(--line)); }\n.status.warn { border-color: color-mix(in srgb, var(--warn) 55%, var(--line)); }\n.status.bad  { border-color: color-mix(in srgb, var(--bad) 55%, var(--line)); }\n.dot { width: 9px; height: 9px; border-radius: 50%; background: var(--muted); flex: none; }\n.dot.good { background: var(--good); } .dot.warn { background: var(--warn); }\n.dot.bad { background: var(--bad); } .dot.info { background: var(--info); }\n\n.output { background: var(--panel-2); border: 1px solid var(--line); border-radius: var(--radius-sm);\n  padding: 13px 15px; }\n.log { font-family: var(--mono); font-size: 0.8rem; line-height: 1.7; background: var(--card);\n  border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 11px 14px;\n  max-height: 220px; overflow-y: auto; white-space: pre-wrap; }\n\n\u002F* ---------- code block + syntax tokens ---------- *\u002F\n.code {\n  font-family: var(--mono); font-size: 0.82rem; line-height: 1.7;\n  background: var(--panel-2); border: 1px solid var(--line); border-radius: var(--radius-sm);\n  padding: 13px 15px; overflow-x: auto; white-space: pre; tab-size: 2;\n}\n.code .tok-sel  { color: var(--accent); }\n.code .tok-prop { color: #86e29b; }\n.code .tok-kw   { color: #ff9bcb; }\n.code .tok-str  { color: #f0c674; }\n.code .tok-num  { color: #f0883e; }\n.code .tok-cmt  { color: var(--faint); font-style: italic; }\n.code .hl { background: color-mix(in srgb, var(--good) 22%, transparent); border-radius: 4px; padding: 0 3px; }\n\n\u002F* ---------- hint \u002F caption ---------- *\u002F\n.hint { font-size: 0.83rem; color: var(--muted); line-height: 1.55; margin: 10px 0 0; }\n.hint code { font-family: var(--mono); color: var(--ink); background: var(--line-soft);\n  padding: 1px 5px; border-radius: 5px; font-size: 0.86em; }\n.hint strong { color: var(--ink); }\n\n\u002F* ---------- banner (feature-support \u002F notices) ---------- *\u002F\n.banner {\n  display: none; margin-bottom: 14px; padding: 11px 14px; border-radius: 11px;\n  font-size: 0.85rem; line-height: 1.5;\n  color: var(--ink); background: color-mix(in srgb, var(--warn) 12%, var(--panel));\n  border: 1px solid color-mix(in srgb, var(--warn) 45%, var(--line));\n}\n.banner.show { display: block; }\n.banner.info { background: color-mix(in srgb, var(--info) 12%, var(--panel));\n  border-color: color-mix(in srgb, var(--info) 45%, var(--line)); }\n.banner code { font-family: var(--mono); background: var(--line-soft); padding: 1px 5px; border-radius: 5px; }\n\n\u002F* ---------- misc atoms ---------- *\u002F\n.pill { display: inline-flex; align-items: center; gap: 6px; font-size: 0.75rem; font-weight: 700;\n  padding: 3px 9px; border-radius: 999px; background: var(--line-soft); color: var(--muted); }\n.pill.good { color: var(--good); background: color-mix(in srgb, var(--good) 16%, transparent); }\n.pill.bad  { color: var(--bad);  background: color-mix(in srgb, var(--bad) 16%, transparent); }\n.mono { font-family: var(--mono); }\n.muted { color: var(--muted); }\n.big-num { font-family: var(--mono); font-size: 1.6rem; font-weight: 800; letter-spacing: -0.02em; }\n\n\u002F* Optional theme toggle button (top-right). Wire it in JS if you want it. *\u002F\n.theme-btn { position: fixed; top: 12px; right: 12px; z-index: 20; }\n\n\u002F* ---------- responsive ---------- *\u002F\n@media (max-width: 560px) {\n  .panel { padding: 14px; }\n  .wrap-controls { gap: 14px; }\n  .btn { padding: 9px 13px; }\n}\n\n\u002F* ---------- reduced motion ---------- *\u002F\n@media (prefers-reduced-motion: reduce) {\n  *, *::before, *::after { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }\n}\n\n\n\u002F* Demo-specific only — base.css owns tokens, panels, buttons, status, log. *\u002F\n  .stat-row { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 10px; }\n  .stat {\n    flex: 1 1 140px;\n    border: 1px solid var(--line);\n    border-radius: var(--radius-sm);\n    background: var(--panel-2);\n    padding: 10px 12px;\n  }\n  .stat .big-num { display: block; font-size: 1.5rem; font-weight: 700; }\n  .stat .label { font-size: 0.72rem; color: var(--muted); text-transform: uppercase; letter-spacing: 0.04em; }\n  .strategy-note {\n    font-size: 0.8rem;\n    color: var(--muted);\n    margin-top: 8px;\n  }\n  .log-line.connect { color: var(--accent); }\n  .log-line.ok { color: var(--good, #3ecf8e); }\n  .log-line.bad { color: var(--bad, #ff6b6b); }\n  .log-line.muted { color: var(--muted); }","const $ = (id) => document.getElementById(id);\n\nlet React, createRoot;\ntry {\n  \u002F\u002F Pinned to the exact version the article verifies.\n  [React, { createRoot }] = await Promise.all([\n    import(\"https:\u002F\u002Fesm.sh\u002Freact@19.3.0\"),\n    import(\"https:\u002F\u002Fesm.sh\u002Freact-dom@19.3.0\u002Fclient?deps=react@19.3.0\"),\n  ]);\n} catch (err) {\n  $(\"boot\").className = \"banner show\";\n  $(\"boot\").innerHTML =\n    \"\u003Cb>React couldn't load from the CDN\u003C\u002Fb> — you're offline, or a network policy blocked esm.sh. \" +\n    \"This demo deliberately runs the \u003Cem>real\u003C\u002Fem> React 19.2+ \u003Ccode>useEffectEvent\u003C\u002Fcode> API rather than \" +\n    \"imitating it, so there's nothing honest to show without it. The article's chat-room examples stand \" +\n    \"on their own; try again with a connection.\";\n  throw err;\n}\n\nif (typeof React.useEffectEvent !== \"function\") {\n  $(\"boot\").className = \"banner show\";\n  $(\"boot\").innerHTML =\n    \"\u003Cb>This React build has no useEffectEvent\u003C\u002Fb> — the pinned CDN version may have changed. \" +\n    \"Strategy C in the article's code samples is still correct against React 19.2+; this playground \" +\n    \"just can't demo it against the copy the CDN served right now.\";\n  throw new Error(\"useEffectEvent missing from pinned React build\");\n}\n\nconst { createElement: h, useEffect, useEffectEvent } = React;\n\n$(\"boot\").hidden = true;\n$(\"app\").hidden = false;\n\nconst logEl = $(\"log\");\nlet reconnects = 0;\nlet notifications = 0;\n\nfunction paintStats() {\n  $(\"reconnectCount\").textContent = String(reconnects);\n  $(\"notifyCount\").textContent = String(notifications);\n}\n\nfunction logLine(text, cls = \"\") {\n  const el = document.createElement(\"div\");\n  el.className = \"log-line \" + cls;\n  el.textContent = text;\n  logEl.prepend(el);\n  while (logEl.childElementCount > 14) logEl.lastElementChild.remove();\n}\n\n\u002F\u002F A ref the parent hands down so each strategy can \"register\" whatever its\n\u002F\u002F currently-open connection's notify callback is. Pressing the button below\n\u002F\u002F always calls whatever is registered right now — exactly like pressing a\n\u002F\u002F real \"test notification\" button in a real chat app.\nconst notifyRegistry = { current: () => logLine(\"no open connection yet\", \"muted\") };\n\n\u002F\u002F --- Strategy A: theme correctly in deps. Correct reads, but reconnects on theme. ---\nfunction RoomDeps({ roomId, theme, onReconnect }) {\n  useEffect(() => {\n    onReconnect();\n    logLine(`🔌 connecting to #${roomId} (theme in deps)…`, \"connect\");\n    notifyRegistry.current = () => {\n      notifications++;\n      paintStats();\n      logLine(`🔔 notification: theme = \"${theme}\" (fresh — but cost a reconnect to get here)`, \"ok\");\n    };\n    return () => logLine(`🔌 disconnecting from #${roomId}`, \"muted\");\n  }, [roomId, theme]);\n  return null;\n}\n\n\u002F\u002F --- Strategy B: theme read directly, left OUT of deps — the classic mistake. ---\nfunction RoomStale({ roomId, theme, onReconnect }) {\n  useEffect(() => {\n    onReconnect();\n    logLine(`🔌 connecting to #${roomId} (theme intentionally omitted)…`, \"connect\");\n    notifyRegistry.current = () => {\n      notifications++;\n      paintStats();\n      \u002F\u002F `theme` here is the value closed over when THIS effect run started —\n      \u002F\u002F it will not change until roomId changes and the effect reruns.\n      logLine(`🔔 notification: theme = \"${theme}\" (captured at connect time — may be stale)`, \"bad\");\n    };\n    return () => logLine(`🔌 disconnecting from #${roomId}`, \"muted\");\n    \u002F\u002F eslint-disable-next-line react-hooks\u002Fexhaustive-deps -- intentionally wrong, see article Stage 1\n  }, [roomId]);\n  return null;\n}\n\n\u002F\u002F --- Strategy C: useEffectEvent. No reconnect on theme, AND always-fresh reads. ---\nfunction RoomEffectEvent({ roomId, theme, onReconnect }) {\n  const onConnected = useEffectEvent(() => {\n    notifications++;\n    paintStats();\n    logLine(`🔔 notification: theme = \"${theme}\" (always current — no reconnect needed)`, \"ok\");\n  });\n\n  useEffect(() => {\n    onReconnect();\n    logLine(`🔌 connecting to #${roomId} (useEffectEvent)…`, \"connect\");\n    notifyRegistry.current = () => onConnected();\n    return () => logLine(`🔌 disconnecting from #${roomId}`, \"muted\");\n  }, [roomId]);\n  return null;\n}\n\nconst STRATEGIES = {\n  deps: {\n    component: RoomDeps,\n    note: \"theme is a dependency, so toggling it disconnects and reconnects — wasteful, but notifications are always correct.\",\n  },\n  stale: {\n    component: RoomStale,\n    note: \"theme is read but not a dependency — no wasted reconnects, but the notification freezes at whatever theme was active when this connection opened.\",\n  },\n  event: {\n    component: RoomEffectEvent,\n    note: \"useEffectEvent splits the two jobs apart: roomId alone decides the connection, and the notification always reads the current theme.\",\n  },\n};\n\nfunction onReconnect() {\n  reconnects++;\n  paintStats();\n}\n\n\u002F\u002F A real React root, mounted into the page (not a detached node) — the whole\n\u002F\u002F point is that useEffectEvent's behavior is the ACTUAL React runtime deciding\n\u002F\u002F what reruns, not a narrated simulation.\nconst mountPoint = document.createElement(\"div\");\n$(\"app\").appendChild(mountPoint);\nconst root = createRoot(mountPoint);\n\nlet appStrategy = \"deps\";\nlet appRoom = \"general\";\nlet appTheme = \"light\";\n\nfunction renderControls() {\n  $(\"strategyNote\").textContent = STRATEGIES[appStrategy].note;\n}\n\nfunction rerenderApp() {\n  \u002F\u002F Switching strategy swaps which component function renders — a different\n  \u002F\u002F element type, so React unmounts the old one and mounts a fresh one. That's\n  \u002F\u002F a real remount, same mechanism as the series' rerender-vs-remount episode.\n  root.render(\n    h(STRATEGIES[appStrategy].component, {\n      key: appStrategy,\n      roomId: appRoom,\n      theme: appTheme,\n      onReconnect,\n    })\n  );\n}\n\n$(\"strategySeg\").addEventListener(\"click\", (e) => {\n  const btn = e.target.closest(\".seg-btn\");\n  if (!btn) return;\n  [...$(\"strategySeg\").children].forEach((b) => b.setAttribute(\"aria-pressed\", String(b === btn)));\n  appStrategy = btn.dataset.strategy;\n  renderControls();\n  logLine(`— switched strategy to ${btn.textContent.trim()} (remounts) —`, \"muted\");\n  rerenderApp();\n});\n\n$(\"roomSeg\").addEventListener(\"click\", (e) => {\n  const btn = e.target.closest(\".seg-btn\");\n  if (!btn) return;\n  [...$(\"roomSeg\").children].forEach((b) => b.setAttribute(\"aria-pressed\", String(b === btn)));\n  appRoom = btn.dataset.room;\n  rerenderApp();\n});\n\n$(\"themeToggle\").addEventListener(\"change\", (e) => {\n  appTheme = e.target.checked ? \"dark\" : \"light\";\n  $(\"themeLabel\").textContent = e.target.checked ? \"Dark theme\" : \"Light theme\";\n  rerenderApp();\n});\n\n$(\"notifyBtn\").addEventListener(\"click\", () => notifyRegistry.current());\n\n$(\"resetBtn\").addEventListener(\"click\", () => {\n  reconnects = 0;\n  notifications = 0;\n  paintStats();\n  logEl.innerHTML = \"\";\n  logLine(\"— counters reset —\", \"muted\");\n});\n\nrenderControls();\nrerenderApp();",{"height":52,"autorun":17},520,{"slug":45,"title":54,"excerpt":55,"coverUrl":56,"vertical":57},"React 19.2 useEffectEvent: Why It Won't Fix Your Deps Array","React's useEffectEvent (stable in 19.2) kills stale closures in Effects without a ref trick — but it's not a deps-array shortcut. Guide + cheat sheet.","\u002Fmedia\u002Fcovers\u002Freact-weekly-useeffectevent-stale-closures.png",{"slug":6},[59,63,67,71,75,79,83,87,91,95,99,103],{"slug":60,"name":61,"articles":62},"webdev","Webdev",142,{"slug":64,"name":65,"articles":66},"javascript","Javascript",115,{"slug":68,"name":69,"articles":70},"frontend","Frontend",86,{"slug":72,"name":73,"articles":74},"tutorial","Tutorial",53,{"slug":76,"name":77,"articles":78},"css","Css",43,{"slug":80,"name":81,"articles":82},"performance","Performance",23,{"slug":84,"name":85,"articles":86},"typescript","Typescript",19,{"slug":88,"name":89,"articles":90},"react","React",17,{"slug":92,"name":93,"articles":94},"browser","Browser",13,{"slug":96,"name":97,"articles":98},"node","Node",12,{"slug":100,"name":101,"articles":102},"programming","Programming",11,{"slug":104,"name":105,"articles":106},"accessibility","Accessibility",9]