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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>IndexedDB — update demo</title>
  <style>
    body {
      font-family: system-ui, sans-serif;
      margin: 0;
      padding: 1.5rem;
      background: #f8fafc;
      color: #334155;
      line-height: 1.6;
    }
    h1 { margin: 0 0 0.5rem; font-size: 1.25rem; color: #0f172a; }
    p { margin: 0 0 1rem; max-width: 460px; }
    button {
      padding: 0.55rem 1rem;
      font-size: 0.9375rem;
      background: #7c3aed;
      color: #fff;
      border: none;
      border-radius: 8px;
      cursor: pointer;
    }
    button:hover { filter: brightness(1.06); }
    button:disabled { opacity: 0.6; cursor: not-allowed; }
    #status, #preview {
      margin-top: 0.75rem;
      padding: 0.75rem 1rem;
      max-width: 460px;
      background: #fff;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      font-size: 0.875rem;
    }
    #status.ok { border-left: 4px solid #22c55e; }
    #status.err { border-left: 4px solid #ef4444; }
    pre { margin: 0.5rem 0 0; font-size: 0.8125rem; white-space: pre-wrap; }
  </style>
</head>
<body>
  <h1>IndexedDB update example</h1>
  <p>Record id 1 is created on load. Click the button to change its <code>value</code> field.</p>

  <button type="button" id="updateBtn" disabled>Update Record</button>
  <p id="status">Opening database&hellip;</p>
  <div id="preview" hidden>
    <strong>Current record:</strong>
    <pre id="previewPre"></pre>
  </div>

  <script>
    var statusEl = document.getElementById('status');
    var previewEl = document.getElementById('preview');
    var previewPre = document.getElementById('previewPre');
    var db;
    var updateCount = 0;

    var request = indexedDB.open('myDatabase', 1);

    request.onupgradeneeded = function (event) {
      event.target.result.createObjectStore('items', { keyPath: 'id' });
    };

    request.onsuccess = function (event) {
      db = event.target.result;

      var tx = db.transaction(['items'], 'readwrite');
      tx.objectStore('items').put({ id: 1, value: 'Original Value' });

      tx.oncomplete = function () {
        statusEl.textContent = 'Database ready. Click Update Record.';
        statusEl.className = 'ok';
        document.getElementById('updateBtn').disabled = false;
        showRecord();
      };
    };

    request.onerror = function (event) {
      statusEl.textContent = 'Database error: ' + event.target.error.message;
      statusEl.className = 'err';
    };

    function showRecord() {
      var tx = db.transaction(['items'], 'readonly');
      var getReq = tx.objectStore('items').get(1);
      getReq.onsuccess = function () {
        previewPre.textContent = JSON.stringify(getReq.result, null, 2);
        previewEl.hidden = false;
      };
    }

    document.getElementById('updateBtn').addEventListener('click', function () {
      var tx = db.transaction(['items'], 'readwrite');
      var store = tx.objectStore('items');
      var getReq = store.get(1);

      getReq.onsuccess = function () {
        var record = getReq.result;
        if (!record) {
          statusEl.textContent = 'Record not found.';
          statusEl.className = 'err';
          return;
        }

        updateCount++;
        record.value = 'Updated Value #' + updateCount;
        store.put(record);
      };

      tx.oncomplete = function () {
        statusEl.textContent = 'Record updated successfully!';
        statusEl.className = 'ok';
        showRecord();
      };

      tx.onerror = function (event) {
        statusEl.textContent = 'Transaction error: ' + event.target.error.message;
        statusEl.className = 'err';
      };
    });
  </script>
</body>
</html>
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