v145 · Web APIs · Upsert Demo

Upsert Demo

Demonstrates IndexedDB's put() in upsert mode — writing a record creates it; writing again updates it — with no pre-read required.

upsert store

IndexedDB—

DB open—

Current record—

Enter a key/value and click Upsert.

code

// Upsert with put() — no pre-read needed
function upsert(db, storeName, record) {
  return new Promise((resolve, reject) => {
    const tx = db.transaction(storeName, 'readwrite');
    const req = tx.objectStore(storeName).put(record);
    req.onsuccess = () => resolve(req.result);
    req.onerror = () => reject(req.error);
  });
}

// First call: creates the record
await upsert(db, 'kv', { id: 'theme', value: 'light' });

// Second call: replaces the record
await upsert(db, 'kv', { id: 'theme', value: 'dark' });

// Result: { id: 'theme', value: 'dark' }
// No read was needed to achieve this — put() is always upsert.

upsert store

code

see also