dart:indexed_db library

A client-side key-value store with support for indexes.

IndexedDB is a web standard API for client-side storage of structured data. By storing data on the client in an IndexedDB, apps can get advantages such as faster performance and persistence.

In IndexedDB, each record is identified by a unique index or key, making data retrieval speedy. You can store structured data, such as images, arrays, and maps using IndexedDB. The standard does not specify size limits for individual data items or for the database itself, but browsers may impose storage limits.

Using indexed_db

The classes in this library provide an interface to the browser's IndexedDB, if it has one. To use this library in your code:

import 'dart:indexed_db';

IndexedDB is almost universally supported in modern web browsers, but a web app can determine if the browser supports IndexedDB with IdbFactory.supported:

if (IdbFactory.supported)
  // Use indexeddb.
else
  // Find an alternative.

Access to the browser's IndexedDB is provided by the app's top-level Window object, which your code can refer to with window.indexedDB. So, for example, here's how to use window.indexedDB to open a database:

Future open() {
  return window.indexedDB.open('myIndexedDB',
      version: 1,
      onUpgradeNeeded: _initializeDatabase)
    .then(_loadFromDB);
}
void _initializeDatabase(VersionChangeEvent e) {
  ...
}
Future _loadFromDB(Database db) {
  ...
}

All data in an IndexedDB is stored within an ObjectStore. To manipulate the database use Transactions.

Other resources

Other options for client-side data storage include:

• Window.localStorage—a basic mechanism that stores data as a Map, and where both the keys and the values are strings.

MDN provides API documentation.