TrJS

True Reactive JavaScript is RxJS like reactive library

Installation and Usage

install via npm

npm i trjsx

In this example we make flow from any iterable data(from the string in this case), take only 2 first values and log in subscribe callback

import { from, take } from 'trjsx';

from('1234')
    .pipe(take(2))
    .subscribe(x => console.log(x)) // will emit only 1, 2

Also it is posible to create several flows from one observable

import { interval, filter, take } from 'trjsx';

const $flow = interval(1000)

$flow.pipe(
    filter(x => x % 2 === 0)    
).subscribe(console.log) // 0, 2, 4 ....

$flow.pipe(
    take(2)  
).subscribe(console.log) // 0, 1 - after the second emited value subscription close

In this example we can easily filter data with filter operator in you flow and even log values with tap operator

import { interval, filter, tap } from 'trjsx';

interval(1000)
    .pipe(
        tap(x => console.log(`log value ${x}`)), // log your flow
        filter((x: any) => x % 2 === 0)
    )
    .subscribe(x => console.log(`subscription ===> ${x}`)) // will emit only even numbers

Every observable returns unsubscribe function on subscribe call

import { interval, timer } from 'trjsx';

const unsubscribe = interval(1000).subscribe(console.log)

timer(1000).subscribe((x) => {
    unsubscribe()
})

It is SCALABLE

It is possible to create your own observables and operators to scale functionanlity

Let's create fromEvent observable

import { Observable, Subscriber } from "../core"

const EE = require('event-emitter')
cosnt ee = new EE()

export function fromEvent(target: EE, eventName: string) {
    return new Observable((subscriber: Subscriber) => {
        const listener = (event) => {
            if (subscriber.closed) {
                target.off(eventName, listener)
            } else {
                subscriber.next(event)
            }
        }

        target.on(eventName, listener)
    })
}

fromEvent(ee, 'click').pipe(take(2)).subscribe(console.log) // 1, 2

ee.emit('click', 1)
ee.emit('click', 2)
ee.emit('click', 3)

And map operator

import { Observable, Subscriber } from "../core"

export const map = (cb: (x: unknown) => unknown) => (prevObservable: Observable) => {
    return new Observable((subscriber: Subscriber) => {
        const unsubscribe = prevObservable.subscribe((value: unknown) => {
            if (subscriber.closed) {
                unsubscribe()
            } else {
                subscriber.next(cb(value))
            }
        })
    })
}

from([1, 2, 3]).pipe(map(x => x * 2)).subscribe(console.log) // 2, 4, 6

Building/Testing

• npm build build everything
• npm test run tests
• npm test:watch run tests in watch mode