What is fake-indexeddb?
The fake-indexeddb npm package is a mock implementation of the IndexedDB API, which is useful for testing and development purposes. It allows developers to simulate IndexedDB operations without relying on a real browser environment.
What are fake-indexeddb's main functionalities?
Creating a Database
This feature allows you to create a new IndexedDB database and an object store within it. The code sample demonstrates how to open a database, handle the upgrade event to create an object store, and log the success event.
const { indexedDB } = require('fake-indexeddb');
const request = indexedDB.open('test-db', 1);
request.onupgradeneeded = function(event) {
const db = event.target.result;
db.createObjectStore('store', { keyPath: 'id' });
};
request.onsuccess = function(event) {
const db = event.target.result;
console.log('Database created:', db);
};
Adding Data to Object Store
This feature allows you to add data to an object store within the IndexedDB database. The code sample demonstrates how to open a database, create a transaction, add data to the object store, and log the completion of the transaction.
const { indexedDB } = require('fake-indexeddb');
const request = indexedDB.open('test-db', 1);
request.onsuccess = function(event) {
const db = event.target.result;
const transaction = db.transaction('store', 'readwrite');
const store = transaction.objectStore('store');
store.add({ id: 1, name: 'John Doe' });
transaction.oncomplete = function() {
console.log('Data added');
};
};
Retrieving Data from Object Store
This feature allows you to retrieve data from an object store within the IndexedDB database. The code sample demonstrates how to open a database, create a transaction, retrieve data from the object store, and log the retrieved data.
const { indexedDB } = require('fake-indexeddb');
const request = indexedDB.open('test-db', 1);
request.onsuccess = function(event) {
const db = event.target.result;
const transaction = db.transaction('store', 'readonly');
const store = transaction.objectStore('store');
const getRequest = store.get(1);
getRequest.onsuccess = function() {
console.log('Data retrieved:', getRequest.result);
};
};
Other packages similar to fake-indexeddb
indexeddbshim
The indexeddbshim package is a polyfill that provides a full implementation of the IndexedDB API for browsers that do not support it natively. Unlike fake-indexeddb, which is primarily for testing, indexeddbshim aims to provide a real IndexedDB experience in environments where it is not available.
localforage
LocalForage is a library that provides a simple API for offline storage, using IndexedDB, WebSQL, or localStorage under the hood. It abstracts away the differences between these storage mechanisms, making it easier to use. While fake-indexeddb is focused on testing, LocalForage is designed for actual application use.
dexie
Dexie is a wrapper library for IndexedDB that provides a more developer-friendly API and additional features like versioning and schema management. It is designed for real-world use in applications, whereas fake-indexeddb is intended for testing purposes.
Fake IndexedDB
This is a pure JS in-memory implementation of the IndexedDB API.
It passes the W3C IndexedDB test suite (a feat that all browsers except Chrome fail) plus a couple hundred more tests just to be sure. It also works well enough to run fairly complex IndexedDB-based software.
Installation
For use with CommonJS (Node.js/Browserify), install through npm:
$ npm install fake-indexeddb
Otherwise, download the bundled version and include it in your page like:
<script type="text/javascript" src="fakeIndexedDB.js"></script>
If you're using AMD, you'll have to shim it.
Use
Functionally, it works exactly like IndexedDB except data is not persisted to disk.
Example usage:
var fakeIndexedDB = require('fake-indexeddb');
var FDBKeyRange = require('fake-indexeddb/lib/FDBKeyRange');
var request = fakeIndexedDB.open('test', 3);
request.onupgradeneeded = function () {
var db = request.result;
var store = db.createObjectStore("books", {keyPath: "isbn"});
store.createIndex("by_title", "title", {unique: true});
store.put({title: "Quarry Memories", author: "Fred", isbn: 123456});
store.put({title: "Water Buffaloes", author: "Fred", isbn: 234567});
store.put({title: "Bedrock Nights", author: "Barney", isbn: 345678});
}
request.onsuccess = function (event) {
var db = event.target.result;
var tx = db.transaction("books");
tx.objectStore("books").index("by_title").get("Quarry Memories").addEventListener('success', function (event) {
console.log('From index:', event.target.result);
});
tx.objectStore("books").openCursor(FDBKeyRange.lowerBound(200000)).onsuccess = function (event) {
var cursor = event.target.result;
if (cursor) {
console.log('From cursor:', cursor.value);
cursor.continue();
}
};
tx.oncomplete = function () {
console.log('All done!');
};
};
Variable names of all the objects are like the normal IndexedDB ones except with F replacing I, e.g. FDBIndex
instead of IDBIndex
.
If you're using the bundled version (not installed through npm), then all of the variables are created and attached to window
, like window.fakeIndexedDB
, window.FDBKeyRange
, etc.
Potential applications:
-
Use as a mock database in unit tests.
-
Use the same API in Node.js and in the browser.
-
Support IndexedDB in old or crappy browsers.
-
Somehow use it within a caching layer on top of IndexedDB in the browser, since IndexedDB can be kind of slow.
-
Abstract the core database functions out, so what is left is a shell that allows the IndexedDB API to easily sit on top of many different backends.
-
Serve as a playground for experimenting with IndexedDB.
License
Apache 2.0