[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"playground-drag-drop-api-dragover-preventdefault-trap":3,"verticals":19,"search-suggestions":58},{"slug":4,"title":5,"summary":6,"html":7,"css":8,"js":9,"config":10,"doc":13},"drag-drop-api-dragover-preventdefault-trap","Drag and Drop — the dragover trap",null,"\u003Cdiv class=\"pg\">\n    \u003Ch1 class=\"pg-title\">🎮 The drop that only happens if you ask for it\u003C\u002Fh1>\n    \u003Cp class=\"pg-sub\">\n      Drag a card between the two columns. The toggle below controls whether the drop zone's\n      \u003Ccode>dragover\u003C\u002Fcode> handler calls \u003Ccode>event.preventDefault()\u003C\u002Fcode> — the one line the\n      browser is silently waiting for before it will ever fire \u003Ccode>drop\u003C\u002Fcode> on that element.\n    \u003C\u002Fp>\n\n    \u003Cdiv class=\"panel\">\n      \u003Cdiv class=\"panel-label\">\u003Cspan class=\"n\">1\u003C\u002Fspan> Controls\u003C\u002Fdiv>\n      \u003Cdiv class=\"btn-row\">\n        \u003Clabel class=\"toggle\">\n          \u003Cinput type=\"checkbox\" id=\"allow\" checked \u002F>\u003Cspan class=\"switch\">\u003C\u002Fspan>\n          \u003Cspan>Call \u003Ccode>preventDefault()\u003C\u002Fcode> in \u003Ccode>dragover\u003C\u002Fcode>\u003C\u002Fspan>\n        \u003C\u002Flabel>\n        \u003Cbutton class=\"btn ghost sm\" id=\"reset\">Reset board\u003C\u002Fbutton>\n      \u003C\u002Fdiv>\n      \u003Cp class=\"hint\">Toggle it off, then try to drop a card — same code, same listener, no drop.\u003C\u002Fp>\n    \u003C\u002Fdiv>\n\n    \u003Cdiv class=\"panel\">\n      \u003Cdiv class=\"panel-label\">\u003Cspan class=\"n\">2\u003C\u002Fspan> Drag a card across\u003C\u002Fdiv>\n      \u003Cdiv class=\"board\">\n        \u003Cdiv class=\"col\" id=\"col-todo\" data-col=\"todo\">\n          \u003Ch3>Backlog\u003C\u002Fh3>\n        \u003C\u002Fdiv>\n        \u003Cdiv class=\"col\" id=\"col-done\" data-col=\"done\">\n          \u003Ch3>Done\u003C\u002Fh3>\n        \u003C\u002Fdiv>\n      \u003C\u002Fdiv>\n\n      \u003Cdiv class=\"counters\">\n        \u003Cdiv>\u003Cdiv class=\"big-num\" id=\"countOk\">0\u003C\u002Fdiv>\u003Cdiv class=\"lbl\">Drops accepted\u003C\u002Fdiv>\u003C\u002Fdiv>\n        \u003Cdiv>\u003Cdiv class=\"big-num\" id=\"countRejected\">0\u003C\u002Fdiv>\u003Cdiv class=\"lbl\">Drops rejected\u003C\u002Fdiv>\u003C\u002Fdiv>\n      \u003C\u002Fdiv>\n\n      \u003Cdiv class=\"status\" style=\"margin-top:12px\">\n        \u003Cspan class=\"dot info\" id=\"dot\">\u003C\u002Fspan>\u003Cspan id=\"statusText\">Ready — drag a card into the other column.\u003C\u002Fspan>\n      \u003C\u002Fdiv>\n      \u003Cp class=\"hint\" id=\"hint\">Right now the toggle is on, so \u003Ccode>dragover\u003C\u002Fcode> cancels the browser's default refusal and the drop will land.\u003C\u002Fp>\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.board { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 6px; }\n  @media (max-width: 560px) { .board { grid-template-columns: 1fr; } }\n  .col {\n    border: 1px dashed var(--line);\n    border-radius: var(--radius-sm);\n    background: var(--panel-2);\n    padding: 10px;\n    min-height: 190px;\n    transition: border-color .15s, background .15s;\n  }\n  .col.over {\n    border-color: var(--accent, #7dd3fc);\n    border-style: solid;\n    background: color-mix(in srgb, var(--panel-2) 80%, var(--accent, #7dd3fc) 20%);\n  }\n  .col.rejected {\n    border-color: #f87171;\n    border-style: solid;\n  }\n  .col h3 { margin: 0 0 8px; font-size: .8rem; text-transform: uppercase; letter-spacing: .04em; color: var(--muted); }\n  .card {\n    background: var(--panel);\n    border: 1px solid var(--line);\n    border-radius: var(--radius-sm);\n    padding: 8px 10px;\n    margin-bottom: 8px;\n    cursor: grab;\n    font-size: .92rem;\n    user-select: none;\n  }\n  .card:active { cursor: grabbing; }\n  .card.dragging { opacity: .4; }\n  .counters { display: flex; gap: 18px; margin-top: 10px; }\n  .counters .big-num { font-size: 1.6rem; }\n  .counters .lbl { font-size: .72rem; color: var(--muted); text-transform: uppercase; letter-spacing: .03em; }","\"use strict\";\n  const $ = (id) => document.getElementById(id);\n  const cols = [$(\"col-todo\"), $(\"col-done\")];\n  let okCount = 0, rejectedCount = 0;\n  let dragEnterDepth = new WeakMap();\n  let draggedRejectedThisDrag = false;\n\n  function setStatus(text, kind = \"info\") {\n    $(\"statusText\").textContent = text;\n    $(\"dot\").className = \"dot \" + kind;\n  }\n\n  function makeCard(label, id) {\n    const el = document.createElement(\"div\");\n    el.className = \"card\";\n    el.draggable = true;\n    el.id = id;\n    el.textContent = label;\n\n    el.addEventListener(\"dragstart\", (e) => {\n      e.dataTransfer.setData(\"text\u002Fplain\", id);\n      e.dataTransfer.effectAllowed = \"move\";\n      el.classList.add(\"dragging\");\n      draggedRejectedThisDrag = false;\n      setStatus(\"Dragging “\" + label + \"” — drop it on the other column.\", \"info\");\n    });\n\n    el.addEventListener(\"dragend\", () => {\n      el.classList.remove(\"dragging\");\n      if (draggedRejectedThisDrag) {\n        rejectedCount++;\n        $(\"countRejected\").textContent = rejectedCount;\n        setStatus(\"Rejected: dragover never called preventDefault(), so drop never fired.\", \"bad\");\n      }\n    });\n\n    return el;\n  }\n\n  function seed() {\n    cols.forEach((c) => {\n      c.querySelectorAll(\".card\").forEach((n) => n.remove());\n      c.classList.remove(\"over\", \"rejected\");\n    });\n    cols[0].appendChild(makeCard(\"Write the migration\", \"card-1\"));\n    cols[0].appendChild(makeCard(\"Review PR #482\", \"card-2\"));\n    cols[1].appendChild(makeCard(\"Fix the flaky test\", \"card-3\"));\n    okCount = 0; rejectedCount = 0;\n    $(\"countOk\").textContent = \"0\";\n    $(\"countRejected\").textContent = \"0\";\n    dragEnterDepth = new WeakMap();\n    setStatus(\"Ready — drag a card into the other column.\", \"info\");\n  }\n\n  cols.forEach((col) => {\n    dragEnterDepth.set(col, 0);\n\n    col.addEventListener(\"dragenter\", (e) => {\n      dragEnterDepth.set(col, (dragEnterDepth.get(col) || 0) + 1);\n      if ($(\"allow\").checked) {\n        col.classList.add(\"over\");\n        col.classList.remove(\"rejected\");\n      } else {\n        col.classList.add(\"rejected\");\n      }\n    });\n\n    col.addEventListener(\"dragleave\", (e) => {\n      const depth = Math.max(0, (dragEnterDepth.get(col) || 0) - 1);\n      dragEnterDepth.set(col, depth);\n      if (depth === 0) {\n        col.classList.remove(\"over\", \"rejected\");\n      }\n    });\n\n    col.addEventListener(\"dragover\", (e) => {\n      if ($(\"allow\").checked) {\n        e.preventDefault(); \u002F\u002F the whole trick\n        e.dataTransfer.dropEffect = \"move\";\n        $(\"hint\").innerHTML = \"\u003Ccode>dragover\u003C\u002Fcode> is calling \u003Ccode>preventDefault()\u003C\u002Fcode> right now — the browser has unlocked this as a valid drop target.\";\n      } else {\n        e.dataTransfer.dropEffect = \"none\";\n        draggedRejectedThisDrag = true;\n        $(\"hint\").innerHTML = \"\u003Ccode>dragover\u003C\u002Fcode> is \u003Cstrong>not\u003C\u002Fstrong> canceling the default — this column will never receive a \u003Ccode>drop\u003C\u002Fcode> event, no matter where you release.\";\n      }\n    });\n\n    col.addEventListener(\"drop\", (e) => {\n      e.preventDefault();\n      dragEnterDepth.set(col, 0);\n      col.classList.remove(\"over\", \"rejected\");\n      const id = e.dataTransfer.getData(\"text\u002Fplain\");\n      const card = document.getElementById(id);\n      if (card && card.parentElement !== col) {\n        col.appendChild(card);\n      }\n      okCount++;\n      $(\"countOk\").textContent = okCount;\n      setStatus(\"Dropped — the drop event fired because dragover allowed it.\", \"good\");\n    });\n  });\n\n  $(\"allow\").addEventListener(\"change\", () => {\n    setStatus(\n      $(\"allow\").checked\n        ? \"preventDefault() is back on — drops will land again.\"\n        : \"preventDefault() is off — every drop attempt will silently bounce.\",\n      \"info\"\n    );\n  });\n\n  $(\"reset\").addEventListener(\"click\", seed);\n\n  seed();",{"height":11,"autorun":12},520,true,{"slug":4,"title":14,"excerpt":15,"coverUrl":16,"vertical":17},"Your Browser Is Rejecting Every Drop On Purpose","A drop zone with a correctly wired drop listener that never fires — no error, no typo, nothing in the console. The browser is silently refusing the drop by design, and only one specific line stops it.","\u002Fmedia\u002Fcovers\u002Fdrag-drop-api-dragover-preventdefault-trap.png",{"slug":18},"dev",[20,34,46],{"id":21,"slug":18,"name":22,"tagline":23,"description":24,"accentFrom":25,"accentTo":26,"icon":27,"defaultLocale":28,"locales":29,"features":31,"position":33},"019fe637-3d33-714b-b57f-23e163ffca0c","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",[28,30],"fa",{"courses":12,"paths":12,"articles":12,"exams":32,"flashcards":32,"packages":12,"community":12,"certificates":12,"teams":12,"commerce":12},false,0,{"id":35,"slug":36,"name":37,"tagline":38,"description":39,"accentFrom":40,"accentTo":25,"icon":41,"defaultLocale":28,"locales":42,"features":44,"position":45},"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","⌘",[28,30,43],"es",{"courses":32,"paths":32,"articles":12,"exams":32,"flashcards":12,"packages":32,"community":12,"certificates":12,"teams":32,"commerce":32},2,{"id":47,"slug":48,"name":49,"tagline":50,"description":51,"accentFrom":52,"accentTo":53,"icon":54,"defaultLocale":28,"locales":55,"features":56,"position":57},"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","◉",[28],{"courses":32,"paths":32,"articles":12,"exams":32,"flashcards":32,"packages":32,"community":12,"certificates":32,"teams":32,"commerce":32},3,[59,63,67,71,75,79,83,87,91,95,98,102],{"slug":60,"name":61,"articles":62},"webdev","Webdev",103,{"slug":64,"name":65,"articles":66},"javascript","Javascript",87,{"slug":68,"name":69,"articles":70},"frontend","Frontend",71,{"slug":72,"name":73,"articles":74},"css","Css",34,{"slug":76,"name":77,"articles":78},"tutorial","Tutorial",32,{"slug":80,"name":81,"articles":82},"typescript","Typescript",15,{"slug":84,"name":85,"articles":86},"react","React",13,{"slug":88,"name":89,"articles":90},"performance","Performance",12,{"slug":92,"name":93,"articles":94},"browser","Browser",9,{"slug":96,"name":97,"articles":94},"node","Node",{"slug":99,"name":100,"articles":101},"html","Html",6,{"slug":103,"name":104,"articles":101},"grammar","Grammar"]