IDBRequest: transaction property
================================

 The **`transaction`** read-only property of the IDBRequest
 interface returns the transaction for the request, that is, the transaction the
 request is being made inside.

 This property can be `null` for requests not made within transactions,
 such as for requests returned from `IDBFactory.open` — in this case
 you're just connecting to a database, so there is no transaction to return. If a
 version upgrade is needed when opening a database then during the
 `upgradeneeded` event handler the
 **`transaction`** property will be an
 `IDBTransaction` with `mode` equal
 to `"versionchange"`, and can be used to access existing object stores and
 indexes, or abort the upgrade. Following the upgrade, the
 **`transaction`** property will again be `null`.

**Note:** This feature is available in Web Workers

Value
-----

An `IDBTransaction`.

Examples
--------

 The following example requests a given record title, `onsuccess` gets the
 associated record from the `IDBObjectStore` (made available
 as `objectStoreTitleRequest.result`), updates
 one property of the record, and then puts the updated record back into the object
 store in another request. The source of the requests is logged to the developer
 console — both originate from the same transaction. For a full working example, see
 our To-do Notifications app
 (View the example live).


```js
const title = "Walk dog";

// Open up a transaction as usual
const objectStore = db
  .transaction(["toDoList"], "readwrite")
  .objectStore("toDoList");

// Get the to-do list object that has this title as it's title
const objectStoreTitleRequest = objectStore.get(title);

objectStoreTitleRequest.onsuccess = () => {
  // Grab the data object returned as the result
  const data = objectStoreTitleRequest.result;

  // Update the notified value in the object to "yes"
  data.notified = "yes";

  // Create another request that inserts the item back
  // into the database
  const updateTitleRequest = objectStore.put(data);

  // Log the transaction that originated this request
  console.log(
    `The transaction that originated this request is ${updateTitleRequest.transaction}`,
  );

  // When this new request succeeds, run the displayData()
  // function again to update the display
  updateTitleRequest.onsuccess = () => {
    displayData();
  };
};
```


 This example shows how a the **`transaction`** property can be
 used during a version upgrade to access existing object stores:


```js
const openRequest = indexedDB.open("db", 2);
console.log(openRequest.transaction); // Will log "null".

openRequest.onupgradeneeded = (event) => {
  console.log(openRequest.transaction.mode); // Will log "versionchange".
  const db = openRequest.result;
  if (event.oldVersion < 1) {
    // New database, create "books" object store.
    db.createObjectStore("books");
  }
  if (event.oldVersion < 2) {
    // Upgrading from v1 database: add index on "title" to "books" store.
    const bookStore = openRequest.transaction.objectStore("books");
    bookStore.createIndex("by\_title", "title");
  }
};

openRequest.onsuccess = () => {
  console.log(openRequest.transaction); // Will log "null".
};
```

Specifications
--------------

| Specification |
| --- |
| Indexed Database API 3.0 # ref-for-dom-idbrequest-transaction① |

Browser compatibility
---------------------

BCD tables only load in the browser with JavaScript enabled. Enable JavaScript to view data.

See also
--------

* Using IndexedDB
* Starting transactions: `IDBDatabase`
* Using transactions: `IDBTransaction`
* Setting a range of keys: `IDBKeyRange`
* Retrieving and making changes to your data: `IDBObjectStore`
* Using cursors: `IDBCursor`
* Reference example: To-do Notifications (View the example live).