mirrorstore: Store data into multiple backends at once

This module allows storage and retrieval of values across multiple backend storage mechanisms at the same time.

Currently, it supports:

• LocalStorage

• IndexedDB

• WebSQL

• Cookies

It will use all available backends when writing.

This module uses Promises for asynchronous operation.

Usage

Install via npm:

npm install --save mirrorstore

In your code:

var MirrorStore = require('mirrorstore');

var ms = new MirrorStore('MyDatabase')

var opts = {
    domain: '.example.com',
    path: '/',
    expires: 60 * 60 * 24 * 7,
    secure: false,
}

// You can store any kind of data...
ms.setItem('userId', '141562716', opts)
// Objects, too!
ms.setItem('prefs', {notify: true, volume: 0.7}, opts)

// Retrieve data by key
ms.getItem('prefs').then(function(value) {
    console.log(value)
})

ms.keys().then(function(keys) {
    console.log(keys)
})

// Remove data by key
ms.removeItem('prefs', opts).then(function() {
    // removed!
})

API

new MirrorStore([databaseName])

Creates a new instance of MirrorStore.

If databaseName is set, it will be used to partition data stored into IndexedDB and WebSQL databases. This value is also visible if browser asks user to allow storing additional data when the backend- and browser-specific limit is reached.

supports() -> Array

Returns an array of supported backends that will be used for storage.

setItem(key, value, [options]) -> Boolean

Write value under a key into all available backends.

Returns true.

See Options below for more information on options argument.

Note: it is not possible to store null or undefined value. If such a value is set, when fetched, it will be returned as undefined, as if it weren't set at all.

getItem(key) -> Mixed

Retrieve the value stored under the key from all available backends.

If value is available under any backend, it will be returned.

If a different value is available via different backends, the value with most occurrences will be returned.

removeItem(key, [options]) -> Boolean

Return the value stored under key from all available backends.

See Options below for more information on options argument.

keys() -> Array

Returns an array of all keys available in all storage backends.

Keys will be retrieved only from the database named during instantiation of this class (the databaseName argument to constructor).

Options

If options map is passed when invoking setItem() or removeItem() methods, it will be passed on to a cookie backend. This is important because a different cookie value can be visible depending on the current page path, whether or not a page is loaded via https, etc.

expires (Mixed)

When the cookie expires.

Possible values:

• Infinity,

• Number of seconds when to expire the cookie (e.g. 180 for 3 minutes),

• Any parseable date or time string (e.g. 2016-01-01 00:00:00),

• An instance of Date class,

• unset: cookie will expire when the browser is closed,

Default: expires is not set.

domain (String)

A string indicating a valid domain where the cookie should be visible. The cookie will also be visible to all subdomains.

Default: Cookie is visible only to the domain or subdomain of the page where the cookie was created, except for Internet Explorer (visible on current domain/subdomain and all nested subdomains, too).

path (String)

A path under which cookie is visible (e.g. /admin/)

Default: /

secure (Boolean)

Either true or false, indicating if the cookie transmission requires a secure protocol (https).

Default: false, cookie will be transferred, regardless of https.

License

BSD 3-Clause License

Copyright (c) 2015, Boris Ćeranić