[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"verticals":3,"playground-vue-weekly-computed-caching-invalidation":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},"vue-weekly-computed-caching-invalidation","Vue computed() caching & invalidation — interactive playground",null,"\u003Cdiv class=\"pg\">\n  \u003Cdiv class=\"pg-title\">computed() caching & invalidation\u003C\u002Fdiv>\n  \u003Cp class=\"pg-sub\">\n    \u003Ccode>total\u003C\u002Fcode> is a real \u003Ccode>computed()\u003C\u002Fcode> deriving \u003Ccode>price × qty\u003C\u002Fcode>\n    (optionally discounted). Watch the difference between \u003Cstrong>writing\u003C\u002Fstrong> to a\n    dependency and \u003Cstrong>reading\u003C\u002Fstrong> the computed — they are not the same event.\n  \u003C\u002Fp>\n\n  \u003Cdiv id=\"boot\" class=\"banner\">\u003C\u002Fdiv>\n\n  \u003Cdiv id=\"app\" hidden>\n\n    \u003Cdiv class=\"panel\">\n      \u003Cdiv class=\"panel-label\">\u003Cspan class=\"n\">1\u003C\u002Fspan> Change dependencies\u003C\u002Fdiv>\n\n      \u003Cdiv class=\"group-label\">Tracked by the getter every run\u003C\u002Fdiv>\n      \u003Cdiv class=\"btn-row\">\n        \u003Cbutton class=\"btn\" id=\"btn-price\">+1 price (now \u003Cspan id=\"price-val\">20\u003C\u002Fspan>)\u003C\u002Fbutton>\n        \u003Cbutton class=\"btn\" id=\"btn-qty\">+1 qty (now \u003Cspan id=\"qty-val\">3\u003C\u002Fspan>)\u003C\u002Fbutton>\n      \u003C\u002Fdiv>\n\n      \u003Cdiv class=\"group-label\">Not read by the getter — a control group\u003C\u002Fdiv>\n      \u003Cdiv class=\"btn-row\">\n        \u003Cbutton class=\"btn ghost\" id=\"btn-unrelated\">+1 unrelated ref (now \u003Cspan id=\"unrelated-val\">0\u003C\u002Fspan>)\u003C\u002Fbutton>\n      \u003C\u002Fdiv>\n\n      \u003Cdiv class=\"group-label\">Conditionally tracked (only when the discount branch runs)\u003C\u002Fdiv>\n      \u003Cdiv class=\"btn-row\">\n        \u003Clabel class=\"toggle\">\n          \u003Cinput type=\"checkbox\" id=\"toggle-discount\" \u002F>\n          \u003Cspan class=\"switch\">\u003C\u002Fspan>\n          Apply discount\n        \u003C\u002Flabel>\n        \u003Cbutton class=\"btn ghost\" id=\"btn-discount\">+5% discount rate (now \u003Cspan id=\"discount-val\">10\u003C\u002Fspan>%)\u003C\u002Fbutton>\n      \u003C\u002Fdiv>\n    \u003C\u002Fdiv>\n\n    \u003Cdiv class=\"panel\">\n      \u003Cdiv class=\"panel-label\">\u003Cspan class=\"n\">2\u003C\u002Fspan> Read the computed\u003C\u002Fdiv>\n      \u003Cdiv class=\"btn-row\">\n        \u003Cbutton class=\"btn primary\" id=\"btn-read\">Read total.value once\u003C\u002Fbutton>\n        \u003Cbutton class=\"btn\" id=\"btn-read5\">Read total.value × 5\u003C\u002Fbutton>\n      \u003C\u002Fdiv>\n\n      \u003Cdiv class=\"total-line\">\n        \u003Cspan>Total (as of last read):\u003C\u002Fspan>\n        \u003Cspan class=\"amount\" id=\"total-display\">$60.00\u003C\u002Fspan>\n        \u003Cspan class=\"status good\" id=\"dirty-pill\">\u003Cspan class=\"dot good\">\u003C\u002Fspan>\u003Cspan id=\"dirty-label\">up to date\u003C\u002Fspan>\u003C\u002Fspan>\n      \u003C\u002Fdiv>\n      \u003Cp class=\"deps\">Tracked dependencies as of the last evaluation:\n        \u003Cspan id=\"deps-chips\">\u003Cspan class=\"chip\">price\u003C\u002Fspan>\u003Cspan class=\"chip\">qty\u003C\u002Fspan>\u003C\u002Fspan>\n      \u003C\u002Fp>\n\n      \u003Cdiv class=\"stats\">\n        \u003Cdiv class=\"stat\">\u003Cdiv class=\"label\">Getter has run\u003C\u002Fdiv>\u003Cdiv class=\"value\" id=\"stat-runs\">1×\u003C\u002Fdiv>\u003C\u002Fdiv>\n        \u003Cdiv class=\"stat\">\u003Cdiv class=\"label\">.value reads\u003C\u002Fdiv>\u003Cdiv class=\"value\" id=\"stat-reads\">1\u003C\u002Fdiv>\u003C\u002Fdiv>\n        \u003Cdiv class=\"stat\">\u003Cdiv class=\"label\">Cache hits\u003C\u002Fdiv>\u003Cdiv class=\"value\" id=\"stat-hits\">0\u003C\u002Fdiv>\u003C\u002Fdiv>\n      \u003C\u002Fdiv>\n    \u003C\u002Fdiv>\n\n    \u003Cdiv class=\"panel\">\n      \u003Cdiv class=\"panel-label\">\u003Cspan class=\"n\">3\u003C\u002Fspan> Timeline\u003C\u002Fdiv>\n      \u003Cp class=\"hint\" style=\"margin-top:0\">\n        Every write is logged the instant it happens. Every read is logged as either a\n        \u003Cstrong>cache hit\u003C\u002Fstrong> (getter did not run) or a \u003Cstrong>recompute\u003C\u002Fstrong>\n        (getter ran, count goes up). Reads and writes never happen at the same moment —\n        that gap is the whole demo.\n      \u003C\u002Fp>\n      \u003Cdiv class=\"log\" id=\"log\" aria-live=\"polite\">\u003C\u002Fdiv>\n    \u003C\u002Fdiv>\n\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  .stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; margin: 4px 0 14px; }\n  .stat { padding: 12px 14px; border: 1px solid var(--line); border-radius: var(--radius-sm); background: var(--panel-2); text-align: center; }\n  .stat .label { font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.5px; color: var(--muted); }\n  .stat .value { font-family: var(--mono); font-size: 1.4rem; font-weight: 800; margin-top: 4px; }\n  .total-line { display: flex; align-items: baseline; gap: 12px; flex-wrap: wrap; margin: 2px 0 6px; }\n  .total-line .amount { font-family: var(--mono); font-size: 2rem; font-weight: 800; color: var(--accent); }\n  .deps { font-size: 0.82rem; color: var(--muted); margin: 0 0 4px; }\n  .deps .chip { display: inline-block; font-family: var(--mono); font-size: 0.76rem; padding: 2px 8px;\n    border-radius: 999px; background: var(--line-soft); color: var(--ink); margin-right: 6px; }\n  .group-label { font-size: 0.78rem; color: var(--muted); margin: 12px 0 6px; }\n  .group-label:first-child { margin-top: 0; }","const $ = (s, r = document) => r.querySelector(s);\n\nlet vue;\ntry {\n  \u002F\u002F Pinned to the exact version this article verifies against.\n  vue = await import(\"https:\u002F\u002Fesm.sh\u002Fvue@3.5.43\");\n} catch (err) {\n  $(\"#boot\").className = \"banner show info\";\n  $(\"#boot\").innerHTML =\n    \"\u003Cb>Vue couldn't load from the CDN\u003C\u002Fb> — you're offline, or a network policy blocked esm.sh. \" +\n    \"This demo runs the \u003Cem>real\u003C\u002Fem> \u003Ccode>computed()\u003C\u002Fcode> implementation rather than imitating its \" +\n    \"caching, so there's nothing honest to show without it. The article's stages stand on their own; \" +\n    \"try again with a connection.\";\n  throw err;\n}\n\nconst { ref, computed } = vue;\n\n$(\"#boot\").hidden = true;\n$(\"#app\").hidden = false;\n\nconst log = $(\"#log\");\nfunction line(text, cls = \"\") {\n  const el = document.createElement(\"div\");\n  el.className = cls;\n  el.textContent = text;\n  log.prepend(el);\n  while (log.childElementCount > 50) log.lastElementChild.remove();\n}\n\nconst price = ref(20);\nconst qty = ref(3);\nconst unrelated = ref(0);\nconst useDiscount = ref(false);\nconst discount = ref(0.1);\n\nlet getterRuns = 0;\nlet reads = 0;\nlet hits = 0;\nlet lastTrackedDiscount = false; \u002F\u002F set inside the getter — reflects the *last actual run's* branch\n\nconst total = computed(() => {\n  getterRuns++;\n  const applyDiscount = useDiscount.value; \u002F\u002F always read: decides the branch\n  lastTrackedDiscount = applyDiscount;      \u002F\u002F bookkeeping only, not reactive state\n  const base = price.value * qty.value;\n  return applyDiscount ? base * (1 - discount.value) : base;\n});\n\n\u002F\u002F A private, non-reactive \"was it dirty before this read?\" detector: peek at\n\u002F\u002F getterRuns before and after touching .value. This never forces a read of\n\u002F\u002F its own — it just observes whether the read we were already doing recomputed.\nfunction readTotal(label) {\n  reads++;\n  const before = getterRuns;\n  const value = total.value;\n  const recomputed = getterRuns > before;\n  if (recomputed) {\n    line(`👁 ${label} → RECOMPUTED (getter run #${getterRuns}) → $${value.toFixed(2)}`, \"good\");\n  } else {\n    hits++;\n    line(`👁 ${label} → cache hit, no recompute → $${value.toFixed(2)}`, \"\");\n  }\n  renderStats(value);\n  return value;\n}\n\nfunction renderStats(value) {\n  $(\"#total-display\").textContent = `$${value.toFixed(2)}`;\n  $(\"#stat-runs\").textContent = `${getterRuns}×`;\n  $(\"#stat-reads\").textContent = String(reads);\n  $(\"#stat-hits\").textContent = String(hits);\n  const chips = [\"price\", \"qty\"];\n  if (lastTrackedDiscount) chips.push(\"discount\");\n  $(\"#deps-chips\").innerHTML = chips.map((c) => `\u003Cspan class=\"chip\">${c}\u003C\u002Fspan>`).join(\"\");\n}\n\nfunction markDirty(depName, willTrack) {\n  const pill = $(\"#dirty-pill\");\n  if (willTrack) {\n    pill.className = \"status warn\";\n    $(\"#dirty-label\").textContent = \"stale — will recompute on next read\";\n    line(`✍️ ${depName} changed → tracked dependency → marked dirty (getter NOT run yet)`, \"bad\");\n  } else {\n    line(`✍️ ${depName} changed → NOT a tracked dependency right now → no invalidation`, \"\");\n  }\n}\n\nfunction markClean() {\n  const pill = $(\"#dirty-pill\");\n  pill.className = \"status good\";\n  $(\"#dirty-label\").textContent = \"up to date\";\n}\n\n$(\"#btn-price\").addEventListener(\"click\", () => {\n  price.value++;\n  $(\"#price-val\").textContent = price.value;\n  markDirty(\"price\", true);\n});\n\n$(\"#btn-qty\").addEventListener(\"click\", () => {\n  qty.value++;\n  $(\"#qty-val\").textContent = qty.value;\n  markDirty(\"qty\", true);\n});\n\n$(\"#btn-unrelated\").addEventListener(\"click\", () => {\n  unrelated.value++;\n  $(\"#unrelated-val\").textContent = unrelated.value;\n  markDirty(\"unrelated\", false);\n});\n\n$(\"#toggle-discount\").addEventListener(\"change\", (e) => {\n  useDiscount.value = e.target.checked;\n  \u002F\u002F useDiscount itself is read unconditionally every run, so it is ALWAYS tracked.\n  markDirty(\"useDiscount\", true);\n});\n\n$(\"#btn-discount\").addEventListener(\"click\", () => {\n  discount.value = Math.min(discount.value + 0.05, 0.95);\n  $(\"#discount-val\").textContent = Math.round(discount.value * 100);\n  \u002F\u002F Only a tracked dependency if the LAST evaluation actually took the discount branch.\n  markDirty(\"discount rate\", lastTrackedDiscount);\n});\n\n$(\"#btn-read\").addEventListener(\"click\", () => {\n  readTotal(\"read total.value\");\n  markClean();\n});\n\n$(\"#btn-read5\").addEventListener(\"click\", () => {\n  for (let i = 1; i \u003C= 5; i++) readTotal(`read #${i} of 5`);\n  markClean();\n});\n\n\u002F\u002F Initial evaluation, exactly like a component's first render reading the computed once.\nreadTotal(\"initial read\");\nmarkClean();",{"height":52,"autorun":17},520,{"slug":45,"title":54,"excerpt":55,"coverUrl":56,"vertical":57},"Vue computed(): What It Caches and When It Reruns","Vue's computed() caches its result and only reruns when a tracked dependency changes, not on every read. The exact caching and invalidation model, verified against Vue 3.5.","\u002Fmedia\u002Fcovers\u002Fvue-weekly-computed-caching-invalidation.png",{"slug":6},[59,63,67,71,75,79,83,87,91,95,99,103],{"slug":60,"name":61,"articles":62},"webdev","Webdev",117,{"slug":64,"name":65,"articles":66},"javascript","Javascript",98,{"slug":68,"name":69,"articles":70},"frontend","Frontend",76,{"slug":72,"name":73,"articles":74},"tutorial","Tutorial",43,{"slug":76,"name":77,"articles":78},"css","Css",37,{"slug":80,"name":81,"articles":82},"typescript","Typescript",17,{"slug":84,"name":85,"articles":86},"performance","Performance",14,{"slug":88,"name":89,"articles":90},"react","React",13,{"slug":92,"name":93,"articles":94},"browser","Browser",11,{"slug":96,"name":97,"articles":98},"node","Node",10,{"slug":100,"name":101,"articles":102},"html","Html",8,{"slug":104,"name":105,"articles":106},"accessibility","Accessibility",7]