Marked.jsというMarkdowonパーサ(text -> html)を使ったMarkdowonエディタ

<!doctype html>
<html lang="ja">
<head>
  <meta charset="utf-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  <title>Markdown Editor — Vanilla JS</title>
  <!-- 最小依存: marked / DOMPurify / highlight.js（任意） をCDNから読み込み -->
  <script src="https://cdn.jsdelivr.net/npm/marked/marked.min.js"></script>
  <script src="https://cdn.jsdelivr.net/npm/dompurify@3.1.6/dist/purify.min.js"></script>
  <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/highlight.js@11.9.0/styles/github-dark.min.css">
  <script src="https://cdn.jsdelivr.net/npm/highlight.js@11.9.0/lib/highlight.min.js"></script>
  <style>
    /* ざっくりとしたUIスタイル。Tailwind等なしで動作可 */
    :root {
      --bg: #0b0b0c;
      --panel: #111214;
      --text: #e7e7ea;
      --muted: #9aa0a6;
      --border: #2a2c30;
      --accent: #4f46e5;
    }
    * { box-sizing: border-box; }
    html, body { height: 100%; }
    body {
      margin: 0; background: var(--bg); color: var(--text);
      font: 14px/1.6 system-ui, -apple-system, Segoe UI, Roboto, "Noto Sans JP", sans-serif;
    }
    header {
      position: sticky; top: 0; z-index: 10;
      backdrop-filter: blur(6px);
      background: color-mix(in oklab, var(--bg) 80%, transparent);
      border-bottom: 1px solid var(--border);
    }
    .wrap { max-width: 1200px; margin: 0 auto; padding: 12px 16px; }
    .title { font-weight: 700; }
    .toolbar { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
    .btn {
      background: var(--panel); border: 1px solid var(--border); color: var(--text);
      padding: 6px 10px; border-radius: 10px; cursor: pointer;
    }
    .btn:hover { background: #17181b; }
    .btn.secondary { color: var(--muted); }
    .spacer { flex: 1; }

    /* 2カラム: 左エディタ / 右プレビュー（中央ドラッグでサイズ変更） */
    .grid {
      display: grid; grid-template-columns: 1fr 8px 1fr; gap: 0; height: calc(100vh - 112px);
    }
    .panel { background: var(--panel); border: 1px solid var(--border); border-radius: 12px; overflow: hidden; display: flex; flex-direction: column; }
    .panel-head { padding: 8px 12px; font-size: 12px; color: var(--muted); border-bottom: 1px solid var(--border); }
    .panel-body { flex: 1; min-height: 0; overflow: auto; }
    textarea {
      width: 100%; height: 100%;
      background: transparent; color: var(--text); border: 0; outline: none;
      font: 13px/1.7 ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
      padding: 12px; resize: none; caret-color: var(--accent);
      tab-size: 2;
    }
    .preview { padding: 12px 16px; }
    .divider { cursor: col-resize; background: var(--border); }

    /* Prose風 見た目（最低限） */
    .preview :is(h1,h2,h3) { margin-top: 1.2em; }
    .preview h1 { font-size: 1.8rem; }
    .preview h2 { font-size: 1.4rem; }
    .preview h3 { font-size: 1.2rem; }
    .preview p, .preview li, .preview code, .preview pre { font-size: 0.95rem; }
    .preview a { color: #93c5fd; }
    .preview blockquote { border-left: 4px solid #394150; padding-left: 12px; color: #c3c7ce; }
    .preview table { border-collapse: collapse; width: 100%; }
    .preview th, .preview td { border: 1px solid var(--border); padding: 6px 8px; }
    .preview code { background: #20222a; padding: 2px 4px; border-radius: 6px; }
    .preview pre { background: #0c0d10; padding: 12px; border-radius: 10px; overflow: auto; }
    .muted { color: var(--muted); }
    .kicker { font-size: 12px; color: var(--muted); }

    @media (max-width: 900px) {
      .grid { grid-template-columns: 1fr; height: auto; gap: 12px; }
      .divider { display: none; }
    }
  </style>
</head>
<body>
  <header>
    <div class="wrap" style="display:flex; gap: 12px; align-items:center;">
      <div class="title">Markdown Editor（Vanilla JS）</div>
      <div class="kicker" id="themeLabel">テーマ: ダーク</div>
      <div class="spacer"></div>
      <div class="toolbar">
        <!-- ツールバー（Markdownシンタックスの挿入） -->
        <button class="btn" data-action="h1">H1</button>
        <button class="btn" data-action="h2">H2</button>
        <button class="btn" data-action="bold"><b>B</b></button>
        <button class="btn" data-action="italic"><i>I</i></button>
        <button class="btn" data-action="strike">S</button>
        <button class="btn" data-action="code">&lt;/&gt;</button>
        <button class="btn" data-action="list">•</button>
        <button class="btn" data-action="num">1.</button>
        <button class="btn" data-action="quote">&gt;</button>
        <button class="btn" data-action="checkbox">☑</button>
        <button class="btn" data-action="hr">―</button>
        <div class="spacer"></div>
        <button class="btn secondary" id="btnTheme">テーマ切替</button>
        <button class="btn secondary" id="btnExport">書き出し(.md)</button>
        <label class="btn secondary" for="fileIn">読み込み(.md)</label>
        <input id="fileIn" type="file" accept=".md,text/markdown,text/plain" style="display:none" />
        <button class="btn secondary" id="btnCopyHtml">HTMLコピー</button>
        <button class="btn secondary" id="btnSample">サンプル読込</button>
        <button class="btn secondary" id="btnClear">クリア</button>
      </div>
    </div>
  </header>

  <main class="wrap">
    <div class="grid" id="grid">
      <!-- 左ペイン: エディタ -->
      <section class="panel" aria-label="エディタ">
        <div class="panel-head">エディタ（Ctrl/⌘+B:太字, Ctrl/⌘+I:斜体）</div>
        <div class="panel-body">
          <textarea id="area" spellcheck="false" placeholder="ここにMarkdownを書いてください…"></textarea>
        </div>
      </section>

      <!-- 仕切り（ドラッグで幅変更） -->
      <div class="divider" id="divider" role="separator" aria-orientation="vertical" aria-label="サイズ変更バー" tabindex="0"></div>

      <!-- 右ペイン: プレビュー -->
      <section class="panel" aria-label="プレビュー">
        <div class="panel-head">プレビュー <span class="muted">（サニタイズ済み）</span></div>
        <div id="preview" class="panel-body preview"></div>
      </section>
    </div>

    <p class="kicker" style="text-align:center; margin: 10px 0 24px;">AutoSave: localStorage / Export: .md / Import: .md / Copy: HTML</p>
  </main>

  <script>
    // ============================
    // 設定・定数
    // ============================
    const LS_KEY = 'md-editor-content-v1';
    const LS_THEME = 'md-editor-theme-v1';

    // サンプル本文
    const SAMPLE = `# ようこそ Markdown エディタへ ✨\n\n右側にプレビューが表示されます。左側で編集してみましょう。\n\n## 主な機能\n- **太字** / *斜体* / ~~取り消し~~\n- [リンク](https://example.com)\n- コード: `console.log('hello')`\n- 箇条書き\n  - サブ項目\n- 引用\n> 引用はこんな感じ\n\n---\n\nチェックボックス:\n- [ ] やること1\n- [x] 完了したこと\n\n表:\n\n| 見出しA | 見出しB |\n| --- | --- |\n| セル1 | セル2 |\n\n\n\n\n\n`; // 末尾余白でスクロールの感覚をよくする

    // markedの設定（GFM, 改行など）
    marked.setOptions({ gfm: true, breaks: true, headerIds: true, mangle: false });

    // 要素参照
    const area = document.getElementById('area');
    const preview = document.getElementById('preview');
    const themeLabel = document.getElementById('themeLabel');

    // ============================
    // テーマ（ダーク/ライト）
    // ============================
    const applyTheme = (t) => {
      if (t === 'light') {
        document.documentElement.style.setProperty('--bg', '#f6f7f8');
        document.documentElement.style.setProperty('--panel', '#ffffff');
        document.documentElement.style.setProperty('--text', '#0f172a');
        document.documentElement.style.setProperty('--muted', '#657084');
        document.documentElement.style.setProperty('--border', '#e5e7eb');
        document.documentElement.style.setProperty('--accent', '#4f46e5');
        themeLabel.textContent = 'テーマ: ライト';
      } else {
        document.documentElement.style.setProperty('--bg', '#0b0b0c');
        document.documentElement.style.setProperty('--panel', '#111214');
        document.documentElement.style.setProperty('--text', '#e7e7ea');
        document.documentElement.style.setProperty('--muted', '#9aa0a6');
        document.documentElement.style.setProperty('--border', '#2a2c30');
        document.documentElement.style.setProperty('--accent', '#4f46e5');
        themeLabel.textContent = 'テーマ: ダーク';
      }
    };
    const initialTheme = localStorage.getItem(LS_THEME) || 'dark';
    applyTheme(initialTheme);

    document.getElementById('btnTheme').addEventListener('click', () => {
      const next = (localStorage.getItem(LS_THEME) || 'dark') === 'dark' ? 'light' : 'dark';
      localStorage.setItem(LS_THEME, next);
      applyTheme(next);
    });

    // ============================
    // レンダリング（Markdown → HTML → サニタイズ → プレビュー）
    // ============================
    const render = () => {
      const raw = marked.parse(area.value || '');
      const clean = DOMPurify.sanitize(raw);
      preview.innerHTML = clean;
      // コードブロックのハイライト
      if (window.hljs) {
        document.querySelectorAll('pre code').forEach((el) => hljs.highlightElement(el));
      }
    };

    // ============================
    // 入出力（保存/読込/エクスポート/HTMLコピー）
    // ============================
    const save = () => localStorage.setItem(LS_KEY, area.value);
    const load = () => localStorage.getItem(LS_KEY) || SAMPLE;

    const exportMd = () => {
      const blob = new Blob([area.value], { type: 'text/markdown;charset=utf-8' });
      const url = URL.createObjectURL(blob);
      const a = document.createElement('a');
      a.href = url; a.download = 'document.md'; a.click();
      URL.revokeObjectURL(url);
    };

    const importMd = (file) => {
      if (!file) return;
      const reader = new FileReader();
      reader.onload = () => { area.value = String(reader.result || ''); onInput(); };
      reader.readAsText(file);
    };

    const copyHtml = async () => {
      try {
        await navigator.clipboard.writeText(preview.innerHTML);
        alert('HTMLをコピーしました');
      } catch (e) {
        alert('コピーに失敗しました');
      }
    };

    // ============================
    // 編集操作（シンタックス挿入）
    // ============================
    const applySyntax = (fn) => {
      const start = area.selectionStart || 0;
      const end = area.selectionEnd || 0;
      const before = area.value.slice(0, start);
      const sel = area.value.slice(start, end);
      const after = area.value.slice(end);
      const replaced = fn(sel);
      area.value = before + replaced + after;
      const caret = (before + replaced).length;
      area.focus();
      area.setSelectionRange(caret, caret);
      onInput();
    };

    const toolbarActions = {
      h1: (s) => `# ${s || '見出し1'}`,
      h2: (s) => `## ${s || '見出し2'}`,
      bold: (s) => `**${s || '太字'}**`,
      italic: (s) => `*${s || '斜体'}*`,
      strike: (s) => `~~${s || '取り消し'}~~`,
      code: (s) => ``${s || 'code'}``,
      list: (s) => (s || '項目').split('\n').map(l => `- ${l}`).join('\n'),
      num: (s) => (s || '項目').split('\n').map((l,i) => `${i+1}. ${l}`).join('\n'),
      quote: (s) => (s || '引用').split('\n').map(l => `> ${l}`).join('\n'),
      checkbox: (s) => (s || 'やること').split('\n').map(l => `- [ ] ${l}`).join('\n'),
      hr: () => `\n\n---\n\n`,
    };

    document.querySelectorAll('[data-action]').forEach(btn => {
      btn.addEventListener('click', () => {
        const key = btn.getAttribute('data-action');
        const fn = toolbarActions[key];
        if (fn) applySyntax(fn);
      });
    });

    // ============================
    // 入力・ショートカット・ドラッグ&ドロップ
    // ============================
    const onInput = () => { save(); render(); };
    area.addEventListener('input', onInput);

    area.addEventListener('keydown', (e) => {
      const accel = e.metaKey || e.ctrlKey;
      if (!accel) return;
      const k = e.key.toLowerCase();
      if (k === 'b') { e.preventDefault(); applySyntax(toolbarActions.bold); }
      if (k === 'i') { e.preventDefault(); applySyntax(toolbarActions.italic); }
    });

    // ファイル読み込み
    document.getElementById('fileIn').addEventListener('change', (e) => {
      const file = e.target.files && e.target.files[0];
      importMd(file);
      e.target.value = '';
    });

    // ボタン群
    document.getElementById('btnExport').addEventListener('click', exportMd);
    document.getElementById('btnCopyHtml').addEventListener('click', copyHtml);
    document.getElementById('btnSample').addEventListener('click', () => { area.value = SAMPLE; onInput(); });
    document.getElementById('btnClear').addEventListener('click', () => { area.value = ''; onInput(); });

    // ドラッグ&ドロップで.md読込
    area.addEventListener('dragover', (e) => e.preventDefault());
    area.addEventListener('drop', (e) => {
      e.preventDefault();
      const file = e.dataTransfer.files && e.dataTransfer.files[0];
      if (file && /\.md$/i.test(file.name)) importMd(file);
    });

    // 仕切りのドラッグで幅変更
    const divider = document.getElementById('divider');
    const grid = document.getElementById('grid');
    let dragging = false;
    const startDrag = () => dragging = true;
    const stopDrag = () => dragging = false;
    const onMove = (clientX) => {
      const rect = grid.getBoundingClientRect();
      const x = Math.min(Math.max(clientX - rect.left, 180), rect.width - 180); // 最小幅を確保
      grid.style.gridTemplateColumns = `${x}px 8px 1fr`;
    };
    divider.addEventListener('mousedown', (e) => { startDrag(); onMove(e.clientX); });
    window.addEventListener('mousemove', (e) => { if (dragging) onMove(e.clientX); });
    window.addEventListener('mouseup', stopDrag);

    // キーボードでも調整（左右キーで±20px）
    divider.addEventListener('keydown', (e) => {
      if (e.key === 'ArrowLeft' || e.key === 'ArrowRight') {
        e.preventDefault();
        const rect = grid.getBoundingClientRect();
        const cols = getComputedStyle(grid).gridTemplateColumns.split(' ');
        const left = parseFloat(cols[0]);
        const delta = e.key === 'ArrowLeft' ? -20 : 20;
        const next = Math.min(Math.max(left + delta, 180), rect.width - 180);
        grid.style.gridTemplateColumns = `${next}px 8px 1fr`;
      }
    });

    // ============================
    // 初期化
    // ============================
    area.value = load();
    render();
  </script>
</body>
</html>

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<!doctype html>

<head>

<title>Markdown Editor — Vanilla JS</title>

<style>

/* ざっくりとしたUIスタイル。Tailwind等なしで動作可 */

:root {

--bg: #0b0b0c;

--panel: #111214;

--text: #e7e7ea;

--muted: #9aa0a6;

--border: #2a2c30;

--accent: #4f46e5;

}

* { box-sizing: border-box; }

html, body { height: 100%; }

body {

margin: 0; background: var(--bg); color: var(--text);

font: 14px/1.6 system-ui, -apple-system, Segoe UI, Roboto, "Noto Sans JP", sans-serif;

}

header {

position: sticky; top: 0; z-index: 10;

backdrop-filter: blur(6px);

background: color-mix(in oklab, var(--bg) 80%, transparent);

border-bottom: 1px solid var(--border);

}

.wrap { max-width: 1200px; margin: 0 auto; padding: 12px 16px; }

.title { font-weight: 700; }

.toolbar { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }

.btn {

background: var(--panel); border: 1px solid var(--border); color: var(--text);

padding: 6px 10px; border-radius: 10px; cursor: pointer;

}

.btn:hover { background: #17181b; }

.btn.secondary { color: var(--muted); }

.spacer { flex: 1; }

/* 2カラム: 左エディタ / 右プレビュー（中央ドラッグでサイズ変更） */

.grid {

display: grid; grid-template-columns: 1fr 8px 1fr; gap: 0; height: calc(100vh - 112px);

}

.panel { background: var(--panel); border: 1px solid var(--border); border-radius: 12px; overflow: hidden; display: flex; flex-direction: column; }

.panel-head { padding: 8px 12px; font-size: 12px; color: var(--muted); border-bottom: 1px solid var(--border); }

.panel-body { flex: 1; min-height: 0; overflow: auto; }

textarea {

width: 100%; height: 100%;

background: transparent; color: var(--text); border: 0; outline: none;

font: 13px/1.7 ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;

padding: 12px; resize: none; caret-color: var(--accent);

tab-size: 2;

}

.preview { padding: 12px 16px; }

.divider { cursor: col-resize; background: var(--border); }

/* Prose風見た目（最低限） */

.preview :is(h1,h2,h3) { margin-top: 1.2em; }

.preview h1 { font-size: 1.8rem; }

.preview h2 { font-size: 1.4rem; }

.preview h3 { font-size: 1.2rem; }

.preview p, .preview li, .preview code, .preview pre { font-size: 0.95rem; }

.preview a { color: #93c5fd; }

.preview blockquote { border-left: 4px solid #394150; padding-left: 12px; color: #c3c7ce; }

.preview table { border-collapse: collapse; width: 100%; }

.preview th, .preview td { border: 1px solid var(--border); padding: 6px 8px; }

.preview code { background: #20222a; padding: 2px 4px; border-radius: 6px; }

.preview pre { background: #0c0d10; padding: 12px; border-radius: 10px; overflow: auto; }

.muted { color: var(--muted); }

.kicker { font-size: 12px; color: var(--muted); }

@media (max-width: 900px) {

.grid { grid-template-columns: 1fr; height: auto; gap: 12px; }

.divider { display: none; }

}

</style>

</head>

<body>

<div class="title">Markdown Editor（Vanilla JS）</div>

<button class="btn secondary" id="btnTheme">テーマ切替</button>

<button class="btn secondary" id="btnCopyHtml">HTMLコピー</button>

<button class="btn secondary" id="btnSample">サンプル読込</button>

</div>

</header>

</div>

</section>

<div class="panel-head">プレビュー <span class="muted">（サニタイズ済み）</span></div>

</section>

</div>

<p class="kicker" style="text-align:center; margin: 10px 0 24px;">AutoSave: localStorage / Export: .md / Import: .md / Copy: HTML</p>

</main>

// ============================

// 設定・定数

// ============================

const LS_KEY = 'md-editor-content-v1';

const LS_THEME = 'md-editor-theme-v1';

// サンプル本文

const SAMPLE = `# ようこそ Markdown エディタへ ✨\n\n右側にプレビューが表示されます。左側で編集してみましょう。\n\n## 主な機能\n- **太字** / *斜体* / ~~取り消し~~\n- [リンク](https://example.com)\n- コード: `console.log('hello')`\n- 箇条書き\n - サブ項目\n- 引用\n> 引用はこんな感じ\n\n---\n\nチェックボックス:\n- [ ] やること1\n- [x] 完了したこと\n\n表:\n\n| 見出しA | 見出しB |\n| --- | --- |\n| セル1 | セル2 |\n\n\n\n\n\n`; // 末尾余白でスクロールの感覚をよくする

// markedの設定（GFM, 改行など）

marked.setOptions({ gfm: true, breaks: true, headerIds: true, mangle: false });

// 要素参照

const area = document.getElementById('area');

const preview = document.getElementById('preview');

const themeLabel = document.getElementById('themeLabel');

// ============================

// テーマ（ダーク/ライト）

// ============================

const applyTheme = (t) => {

if (t === 'light') {

document.documentElement.style.setProperty('--bg', '#f6f7f8');

document.documentElement.style.setProperty('--panel', '#ffffff');

document.documentElement.style.setProperty('--text', '#0f172a');

document.documentElement.style.setProperty('--muted', '#657084');

document.documentElement.style.setProperty('--border', '#e5e7eb');

document.documentElement.style.setProperty('--accent', '#4f46e5');

themeLabel.textContent = 'テーマ: ライト';

} else {

document.documentElement.style.setProperty('--bg', '#0b0b0c');

document.documentElement.style.setProperty('--panel', '#111214');

document.documentElement.style.setProperty('--text', '#e7e7ea');

document.documentElement.style.setProperty('--muted', '#9aa0a6');

document.documentElement.style.setProperty('--border', '#2a2c30');

document.documentElement.style.setProperty('--accent', '#4f46e5');

themeLabel.textContent = 'テーマ: ダーク';

}

};

const initialTheme = localStorage.getItem(LS_THEME) || 'dark';

applyTheme(initialTheme);

document.getElementById('btnTheme').addEventListener('click', () => {

const next = (localStorage.getItem(LS_THEME) || 'dark') === 'dark' ? 'light' : 'dark';

localStorage.setItem(LS_THEME, next);

applyTheme(next);

});

// ============================

// レンダリング（Markdown → HTML → サニタイズ → プレビュー）

// ============================

const render = () => {

const raw = marked.parse(area.value || '');

const clean = DOMPurify.sanitize(raw);

preview.innerHTML = clean;

// コードブロックのハイライト

if (window.hljs) {

document.querySelectorAll('pre code').forEach((el) => hljs.highlightElement(el));

}

};

// ============================

// 入出力（保存/読込/エクスポート/HTMLコピー）

// ============================

const save = () => localStorage.setItem(LS_KEY, area.value);

const load = () => localStorage.getItem(LS_KEY) || SAMPLE;

const exportMd = () => {

const blob = new Blob([area.value], { type: 'text/markdown;charset=utf-8' });

const url = URL.createObjectURL(blob);

const a = document.createElement('a');

a.href = url; a.download = 'document.md'; a.click();

URL.revokeObjectURL(url);

};

const importMd = (file) => {

if (!file) return;

const reader = new FileReader();

reader.onload = () => { area.value = String(reader.result || ''); onInput(); };

reader.readAsText(file);

};

const copyHtml = async () => {

try {

await navigator.clipboard.writeText(preview.innerHTML);

alert('HTMLをコピーしました');

} catch (e) {

alert('コピーに失敗しました');

}

};

// ============================

// 編集操作（シンタックス挿入）

// ============================

const applySyntax = (fn) => {

const start = area.selectionStart || 0;

const end = area.selectionEnd || 0;

const before = area.value.slice(0, start);

const sel = area.value.slice(start, end);

const after = area.value.slice(end);

const replaced = fn(sel);

area.value = before + replaced + after;

const caret = (before + replaced).length;

area.focus();

area.setSelectionRange(caret, caret);

onInput();

};

const toolbarActions = {

h1: (s) => `# ${s || '見出し1'}`,

h2: (s) => `## ${s || '見出し2'}`,

bold: (s) => `**${s || '太字'}**`,

italic: (s) => `*${s || '斜体'}*`,

strike: (s) => `~~${s || '取り消し'}~~`,

code: (s) => ``${s || 'code'}``,

list: (s) => (s || '項目').split('\n').map(l => `- ${l}`).join('\n'),

num: (s) => (s || '項目').split('\n').map((l,i) => `${i+1}. ${l}`).join('\n'),

quote: (s) => (s || '引用').split('\n').map(l => `> ${l}`).join('\n'),

checkbox: (s) => (s || 'やること').split('\n').map(l => `- [ ] ${l}`).join('\n'),

hr: () => `\n\n---\n\n`,

};

document.querySelectorAll('[data-action]').forEach(btn => {

btn.addEventListener('click', () => {

const key = btn.getAttribute('data-action');

const fn = toolbarActions[key];

if (fn) applySyntax(fn);

});

// ============================

// 入力・ショートカット・ドラッグ&ドロップ

// ============================

const onInput = () => { save(); render(); };

area.addEventListener('input', onInput);

area.addEventListener('keydown', (e) => {

const accel = e.metaKey || e.ctrlKey;

if (!accel) return;

const k = e.key.toLowerCase();

if (k === 'b') { e.preventDefault(); applySyntax(toolbarActions.bold); }

if (k === 'i') { e.preventDefault(); applySyntax(toolbarActions.italic); }

});

// ファイル読み込み

document.getElementById('fileIn').addEventListener('change', (e) => {

const file = e.target.files && e.target.files[0];

importMd(file);

e.target.value = '';

});

// ボタン群

document.getElementById('btnExport').addEventListener('click', exportMd);

document.getElementById('btnCopyHtml').addEventListener('click', copyHtml);

document.getElementById('btnSample').addEventListener('click', () => { area.value = SAMPLE; onInput(); });

document.getElementById('btnClear').addEventListener('click', () => { area.value = ''; onInput(); });

// ドラッグ&ドロップで.md読込

area.addEventListener('dragover', (e) => e.preventDefault());

area.addEventListener('drop', (e) => {

e.preventDefault();

const file = e.dataTransfer.files && e.dataTransfer.files[0];

if (file && /\.md$/i.test(file.name)) importMd(file);

});

// 仕切りのドラッグで幅変更

const divider = document.getElementById('divider');

const grid = document.getElementById('grid');

let dragging = false;

const startDrag = () => dragging = true;

const stopDrag = () => dragging = false;

const onMove = (clientX) => {

const rect = grid.getBoundingClientRect();

const x = Math.min(Math.max(clientX - rect.left, 180), rect.width - 180); // 最小幅を確保

grid.style.gridTemplateColumns = `${x}px 8px 1fr`;

};

divider.addEventListener('mousedown', (e) => { startDrag(); onMove(e.clientX); });

window.addEventListener('mousemove', (e) => { if (dragging) onMove(e.clientX); });

window.addEventListener('mouseup', stopDrag);

// キーボードでも調整（左右キーで±20px）

divider.addEventListener('keydown', (e) => {

if (e.key === 'ArrowLeft' || e.key === 'ArrowRight') {

e.preventDefault();

const rect = grid.getBoundingClientRect();

const cols = getComputedStyle(grid).gridTemplateColumns.split(' ');

const left = parseFloat(cols[0]);

const delta = e.key === 'ArrowLeft' ? -20 : 20;

const next = Math.min(Math.max(left + delta, 180), rect.width - 180);

grid.style.gridTemplateColumns = `${next}px 8px 1fr`;

}

});

// ============================

// 初期化

// ============================

area.value = load();

render();

</script>

</body>

</html>

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