{{APIRef("IndexedDB")}}
The IDBDatabase interface of the IndexedDB API provides a connection to a database; you can use an IDBDatabase object to open a transaction on your database then create, manipulate, and delete objects (data) in that database. The interface provides the only way to get and manage versions of the database.
{{AvailableInWorkers}}
Note: Everything you do in IndexedDB always happens in the context of a transaction, representing interactions with data in the database. All objects in IndexedDB — including object stores, indexes, and cursors — are tied to a particular transaction. Thus, you cannot execute commands, access data, or open anything outside of a transaction.
Inherits from: EventTarget
Fires when a database structure change ({{domxref("IDBOpenDBRequest.onupgradeneeded")}} event or {{domxref("IDBFactory.deleteDatabase()")}} was requested elsewhere (most probably in another window/tab on the same computer). This is different from the version change transaction (see {{domxref("IDBVersionChangeEvent")}}), but it is related.
In the following code snippet, we open a database asynchronously ({{domxref("IDBFactory")}}), handle success and error cases, and create a new object store in the case that an upgrade is needed ({{ domxref("IDBdatabase") }}). For a complete working example, see our To-do Notifications app (view example live.)
// Let us open our database
var DBOpenRequest = window.indexedDB.open("toDoList", 4);
// these two event handlers act on the IDBDatabase object, when the database is opened successfully, or not
DBOpenRequest.onerror = function(event) {
note.innerHTML += '<li>Error loading database.</li>';
};
DBOpenRequest.onsuccess = function(event) {
note.innerHTML += '<li>Database initialised.</li>';
// store the result of opening the database in the db variable. This is used a lot later on
db = DBOpenRequest.result;
// Run the displayData() function to populate the task list with all the to-do list data already in the IDB
displayData();
};
// This event handles the event whereby a new version of the database needs to be created
// Either one has not been created before, or a new version number has been submitted via the
// window.indexedDB.open line above
DBOpenRequest.onupgradeneeded = function(event) {
var db = event.target.result;
db.onerror = function(event) {
note.innerHTML += '<li>Error loading database.</li>';
};
// Create an objectStore for this database using IDBDatabase.createObjectStore
var objectStore = db.createObjectStore("toDoList", { keyPath: "taskTitle" });
// define what data items the objectStore will contain
objectStore.createIndex("hours", "hours", { unique: false });
objectStore.createIndex("minutes", "minutes", { unique: false });
objectStore.createIndex("day", "day", { unique: false });
objectStore.createIndex("month", "month", { unique: false });
objectStore.createIndex("year", "year", { unique: false });
objectStore.createIndex("notified", "notified", { unique: false });
note.innerHTML += '<li>Object store created.</li>';
};
This next line opens up a transaction on the Database, then opens an object store that we can then manipulate the data inside of.
var objectStore = db.transaction('toDoList').objectStore('toDoList');
| Specification | Status | Comment |
|---|---|---|
| {{SpecName('IndexedDB', '#idl-def-IDBDatabase', 'IDBDatabase')}} | {{Spec2('IndexedDB')}} | Initial version |
| {{SpecName("IndexedDB 2", "#database-interface", "IDBDatabase")}} | {{Spec2("IndexedDB 2")}} |
| Feature | Chrome | Firefox (Gecko)[1] | Internet Explorer | Opera | Safari (WebKit) |
|---|---|---|---|---|---|
| Basic support | 23 {{property_prefix("webkit")}} 24 |
10 {{property_prefix("moz")}} {{CompatGeckoDesktop(16)}} |
10, partial | 15 | 7.1 |
| Available in workers | {{CompatVersionUnknown}} | {{CompatGeckoDesktop(37)}} | {{CompatUnknown}} | {{CompatVersionUnknown}} | {{CompatUnknown}} |
| {{event("close")}} event | {{CompatVersionUnknown}} | {{CompatGeckoDesktop(50)}} | {{CompatUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} |
| Feature | Android | Android Webview | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile | Chrome for Android |
|---|---|---|---|---|---|---|---|---|
| Basic support | 4.4 | {{CompatVersionUnknown}} | {{CompatGeckoMobile(22)}} | 1.0.1 | 10 | 22 | 8 | {{CompatVersionUnknown}} |
| Available in workers | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatGeckoMobile(37)}} | {{CompatVersionUnknown}} | {{CompatUnknown}} | {{CompatVersionUnknown}} | {{CompatUnknown}} | {{CompatVersionUnknown}} |
| {{event("close")}} event | {{CompatUnknown}} | {{CompatVersionUnknown}} | {{CompatGeckoMobile(50)}} | {{CompatUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | {{CompatVersionUnknown}} |
[1] As of Firefox 40, IndexedDB transactions have relaxed durability guarantees to increase performance (see {{Bug("1112702")}}). Previously in a readwrite transaction {{domxref("IDBTransaction.oncomplete")}} was fired only when all data was guaranteed to have been flushed to disk. In Firefox 40+ the complete event is fired after the OS has been told to write the data but potentially before that data has actually been flushed to disk. The complete event may thus be delivered quicker than before, however, there exists a small chance that the entire transaction will be lost if the OS crashes or there is a loss of system power before the data is flushed to disk. Since such catastrophic events are rare most consumers should not need to concern themselves further. If you must ensure durability for some reason (e.g. you're storing critical data that cannot be recomputed later) you can force a transaction to flush to disk before delivering the complete event by creating a transaction using the experimental (non-standard) readwriteflush mode (see {{domxref("IDBDatabase.transaction")}}).