spitfirejs v1.0.2

DEPRECATED: Please use Observux instead. It has the same functionality with a simpler API.

Spitfire.js

A tiny reactive data model library.

Requirements

• RxJS

Installation

npm install rxjs
npm install spitfirejs

API

Model.constructor(source)

Convenience class for extension and lazy model transformation. A Model instance gets transformed into a reactive data model when its prototype property state$ is called for the first time. If a source object is available in the constructor, its own enumerable properties are copied onto the new Model instance.

import {Model} from 'spitfirejs'

const model = new Model({foo: 'bar'})  // => Model { foo: 'bar' }

model.hasOwnProperty('state$')  // => false; the model is not transformed yet
model.state$  // => Observable<object>; the property `state$` gets called for the first time
model.hasOwnProperty('state$')  // => true; the model is now transformed

Model.transform(source)

Transforms the source object into a reactive model by redefining its own enumerable non-function properties into proxies which handle values via getters and setters using RxJS BehaviorSubject instances. The combined latest properties are accessible via the state$ property, an RxJS Observable stream of previous and next states. Returns the frozen source object.

import {Model} from 'spitfirejs'

const source = { foo: 'bar' }
const model = Model.transform(source)  // => Object { foo: 'bar' }

model === source  // => true; the original source object is transformed into a model
model.hasOwnProperty('state$')  // => true; the model is immediately transformed

Usage

The reactive data model can be used to store any data and immediately notify its state$ observers of any state changes. A simple example:

import {Model} from 'spitfirejs'

class Counter extends Model {
    constructor() {
        super()
        this.count = 0
    }

    increment() {
        this.count += 1
    }

    decrement() {
        this.count -= 1
    }
}

const counter = new Counter()  // => Counter { count: 0 }

const subscriber1 = counter.state$.subscribe(state => {
    console.log(state.next.count)
})  // `0` is logged on subscription
counter.increment()  // `1` is logged on change
counter.decrement()  // `0` is logged on change

subscriber1.unsubscribe()
counter.increment()  // the count is incremented, but nothing is logged because there are no subscribers
const subscriber2 = counter.state$.subscribe(state => {
    console.log(state.next.count)
}  // `1` is logged on subscription

Since each state$ property is a regular RxJS Observable instance, they can be used with any RxJS operators, e.g. for filtering, transforming or combining multiple states. An example:

import {Model} from 'spitfirejs'
import {Observable} from 'rxjs/Observable'
import 'rxjs/add/observable/combineLatest'
import 'rxjs/add/operators/map'
import 'rxjs/add/operators/filter'

class Movie extends Model {
    constructor(name) {
        super()
        this.name = name
        this.lastWatched = null
    }

    watch() {
        this.lastWatched = new Date()
    }
}

const movie1 = new Movie("Monty Python and the Holy Grail")
const movie2 = new Movie("Monty Python's Life of Brian")
const movie3 = new Movie("Monty Python's The Meaning of Life")

// Observe the order of watched movies when all movies have been watched at least once
Observable.combineLatest(movie1.state$, movie2.state$, movie3.state$)
    .map(states => states.map(state => state.next))  // Discard the previous state
    .filter(movies => movies.every(movie => movie.lastWatched))  // Proceed only if all movies have been watched
    .map(movies => movies.sort((a, b) => a.lastWatched - b.lastWatched)) // Sort movies by the time they were last watched
    .map(movies => movies.map(movie => movie.name))  // Take only movie names
    .subscribe(watchOrder => {
        console.log(watchOrder)
    })

movie1.watch()  // Nothing happens, because not all movies have been watched yet
movie2.watch()  // Nothing happens, because not all movies have been watched yet
movie3.watch()  // ["Monty Python and the Holy Grail", "Monty Python's Life of Brian", "Monty Python's The Meaning of Life"]
movie2.watch()  // ["Monty Python and the Holy Grail", "Monty Python's The Meaning of Life", "Monty Python's Life of Brian"]
movie1.watch()  // ["Monty Python's The Meaning of Life", "Monty Python's Life of Brian", "Monty Python and the Holy Grail"]

Resources

• RxJS operators