localForage

localForage is a fast and simple storage library for JavaScript. localForage improves the offline experience of your web app by using asynchronous storage (IndexedDB or WebSQL) with a simple, localStorage-like API.

localForage uses localStorage in browsers with no IndexedDB or WebSQL support. See the wiki for detailed compatibility info.

To use localForage, just drop a single JavaScript file into your page:

<script src="localforage.js"></script>
<script>localforage.getItem('something', myCallback);</script>

Download the latest localForage from GitHub, or install with npm:

npm install localforage

or bower:

bower install localforage

localForage is compatible with browserify.

Support

Lost? Need help? Try the localForage API documentation.

If you're stuck using the library, running the tests, or want to contribute to localForage, you can visit irc.freenode.net and head to the #localforage channel to ask questions about localForage.

The best person to ask about localForage is tofumatt, who is usually online from 8am-8pm GMT (London Time).

How to use localForage

Callbacks vs Promises

Because localForage uses async storage, it has an async API. It's otherwise exactly the same as the localStorage API.

localForage has a dual API that allows you to either use Node-style callbacks or Promises. If you are unsure which one is right for you, it's recommended to use Promises.

Here's an example of the Node-style callback form:

localforage.setItem('key', 'value', function (err) {
  // if err is non-null, we got an error
  localforage.getItem('key', function (err, value) {
    // if err is non-null, we got an error. otherwise, value is the value 
  });
});

And the Promise form:

localforage.setItem('key', 'value').then(function () {
  return localforage.getItem('key');
}).then(function (value) {
  // we got our value
}).catch(function (err) {
  // we got an error
});

For more examples, please visit the API docs.

Storing Blobs, TypedArrays, and other JS objects

You can store any type in localForage; you aren't limited to strings like in localStorage. Even if localStorage is your storage backend, localForage automatically does JSON.parse() and JSON.stringify() when getting/setting values.

localForage supports storing all native JS objects that can be serialized to JSON, as well as ArrayBuffers, Blobs, and TypedArrays. Check the API docs for a full list of types supported by localForage.

All types are supported in every storage backend, though storage limits in localStorage make storing many large Blobs impossible.

Configuration

You can set database information with the config() method. Available options are driver, name, storeName, version, size, and description.

Example:

localforage.config({
    driver      : localforage.WEBSQL, // Force WebSQL; same as using setDriver()
    name        : 'myApp',
    version     : 1.0,
    size        : 4980736, // Size of database, in bytes. WebSQL-only for now.
    storeName   : 'keyvaluepairs', // Should be alphanumeric, with underscores.
    description : 'some description'
});

Note: you must call config() before you interact with your data. This means calling config() before using getItem(), setItem(), removeItem(), clear(), key(), keys() or length().

Multiple instances

You can create multiple instances of localForage that point to different stores using createInstance. All the configuration options used by config are supported.

var store = localforage.createInstance({
  name: "nameHere"
});

var otherStore = localforage.createInstance({
  name: "otherName"
});

// Setting the key on one of these doesn't affect the other.
store.setItem("key", "value");
otherStore.setItem("key", "value2");

RequireJS

You can use localForage with RequireJS:

define(['localforage'], function(localforage) {
    // As a callback:
    localforage.setItem('mykey', 'myvalue', console.log);

    // With a Promise:
    localforage.setItem('mykey', 'myvalue').then(console.log);
});

Browserify and Webpack

localForage 1.3+ works with both Browserify and Webpack. If you're using an earlier version of localForage and are having issues with Browserify or Webpack, please upgrade to 1.3.0 or above.

If you're using localForage in your own build system (eg. browserify or webpack) make sure you have the required plugins and transformers installed (eg. npm install --save-dev babel-plugin-system-import-transformer).

TypeScript

To import localForage in TypeScript:

import localForage = require("localforage");

Note that the ES6 style import is not supported for our module type. Check out the following to know why:

Framework Support

If you use a framework listed, there's a localForage storage driver for the models in your framework so you can store data offline with localForage. We have drivers for the following frameworks:

If you have a driver you'd like listed, please open an issue to have it added to this list.

Custom Drivers

You can create your own driver if you want; see the defineDriver API docs.

There is a list of custom drivers on the wiki.

Working on localForage

You'll need node/npm and bower.

To work on localForage, you should start by forking it and installing its dependencies. Replace USERNAME with your GitHub username and run the following:

# Install bower globally if you don't have it:
npm install -g bower

# Replace USERNAME with your GitHub username:
git clone git@github.com:USERNAME/localForage.git
cd localForage
npm install
bower install

Omitting the bower dependencies will cause the tests to fail!

Running Tests

You need PhantomJS installed to run local tests. Run npm test (or, directly: grunt test). Your code must also pass the linter.

localForage is designed to run in the browser, so the tests explicitly require a browser environment. Local tests are run on a headless WebKit (using PhantomJS).

When you submit a pull request, tests will be run against all browsers that localForage supports on Travis CI using Sauce Labs.

License

This program is free software; it is distributed under an Apache License.

sheppard/localForage