birkin

simple and immutable key/value-bag for storing session and configuration data in client-side applications

Installation

$ npm install birkin --save

In ES5:

var Bag = require('birkin');
var sessionbag = new Bag();

Using Babel / ES6:

import Bag from 'birkin';
const sessionbag = new Bag();

API

Constructor(objects...)

The instance can be passed any number of objects on instantiation that will serve as base data:

var emptyBag = new Bag();
var prepopulated = new Bag({key: 'value'});
var numbers = new Bag({one: 1}, {two: 2}, {three: 3});

set(key, value)

Associates any value with the given key:

var sessionbag = new Bag();
sessionbag.set('some-string', 'Christ is risen');
sessionbag.set('some-array', ['foo', 'bar', 'baz']);

set(objects...)

Merges the given object into the store:

var sessionbag = new Bag();
sessionbag.set({a: 1, b: 2, c: 3});
sessionbag.set({d: 4}, {e: 5});

get(key)

Retrieves a value by the given key:

sessionbag.set('message', 'Christ is risen');
sessionbag.get('message'); // => 'Christ is risen'
sessionbag.get('notset'); // => undefined

get(keys...)

Retrieves a value inside a stored object:

var sessionbag = new Bag();
sessionbag.set('nested', { christ: { is: {risen: 'not too sure' } } });
sessionbag.get('nested', 'christ', 'is', 'risen'); // => 'not too sure'

get()

Retrieves the store as an object:

var sessionbag = new Bag();
sessionbag.set('foo', 'bar');
sessionbag.get(); // => {foo: 'bar'}

has(key)

Checks if the given key exists:

var sessionbag = new Bag();
sessionbag.set('foo', 'bar');
sessionbag.has('foo'); // => true
sessionbag.has('bar'); // => false

has()

Checks if the instance contains any keys:

var sessionbag = new Bag();
sessionbag.has(); // => false
sessionbag.set('foo', 'bar');
sessionbag.has(); // => true

Immutability

birkin is designed to be immutable. Keys cannot be overridden or unset. Returned values will be clones. This enforces well designed data structures and handling.

var sessionbag = new Bag();
sessionbag.set('foo', 'bar');
sessionbag.set('foo', 'baz');
sessionbag.set({ foo: 'qux', bar: 'foo'});
sessionbag.get(); // => {foo: 'bar', bar: 'foo'}
sessionbag.set('obj', {a: 'b'});
var obj = sessionbag.get('obj');
obj.a = 'c';
sessionbag.get('obj'); // => {a: 'b'}

If you are sure that mutating values is the right approach for your problem at hand, do so explicitly:

var sessionbag = new Bag({key: 'value'});
var data = sessionbag.get();
data.key = 'updated value';
sessionbag = new Bag(data);
sessionbag.get('key'); // => 'updated value'

License

MIT © Frederik Ring