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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 cursor.update()</title>
  <style>
    body { font-family: system-ui, sans-serif; margin: 1.5rem; line-height: 1.5; }
    button { margin-right: 0.5rem; margin-bottom: 0.5rem; padding: 0.5rem 0.9rem; cursor: pointer; }
    #status { margin-top: 1rem; }
  </style>
</head>
<body>
  <h1>cursor.update()</h1>
  <p>Rename every contact named Alex while iterating.</p>

  <button type="button" id="seedBtn" disabled>Seed samples</button>
  <button type="button" id="updBtn" disabled>Rename via cursor</button>
  <button type="button" id="listBtn" disabled>List names</button>

  <p id="status">Opening database&hellip;</p>

  <script>
    var statusEl = document.getElementById('status');
    var db;

    var openReq = indexedDB.open('tryitUpdateCursor', 1);

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

    openReq.onsuccess = function (event) {
      db = event.target.result;
      statusEl.textContent = 'Ready.';
      ['seedBtn', 'updBtn', 'listBtn'].forEach(function (id) {
        document.getElementById(id).disabled = false;
      });
    };

    document.getElementById('seedBtn').addEventListener('click', function () {
      var tx = db.transaction(['contacts'], 'readwrite');
      var store = tx.objectStore('contacts');
      store.put({ id: 1, name: 'Alex' });
      store.put({ id: 2, name: 'Sam Lee' });
      tx.oncomplete = function () {
        statusEl.textContent = 'Seeded Alex and Sam Lee.';
      };
    });

    document.getElementById('updBtn').addEventListener('click', function () {
      var changed = 0;
      var tx = db.transaction(['contacts'], 'readwrite');
      var req = tx.objectStore('contacts').openCursor();

      req.onsuccess = function () {
        var cursor = req.result;
        if (!cursor) return;
        if (cursor.value.name === 'Alex') {
          var next = Object.assign({}, cursor.value, { name: 'Alex Rivera' });
          cursor.update(next);
          changed += 1;
        }
        cursor.continue();
      };

      tx.oncomplete = function () {
        statusEl.textContent = 'cursor.update() changed ' + changed + ' row(s).';
      };
    });

    document.getElementById('listBtn').addEventListener('click', function () {
      var tx = db.transaction(['contacts'], 'readonly');
      var req = tx.objectStore('contacts').getAll();
      req.onsuccess = function () {
        var rows = req.result || [];
        statusEl.textContent = rows.length
          ? rows.map(function (r) { return r.id + ':' + r.name; }).join(', ')
          : 'Store empty.';
      };
    });
  </script>
</body>
</html>
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IndexedDB Update — cursor.update()
