react.reactive

React Reactive Programming Toolkit

Inspired by bacon.react.html, react-combinators and Cycle.js but has no external dependencies (except React) and works with any reactive library that is compatible with ECMAScript Observable spec

Example

import React from "react"
import Kefir from "kefir"
import R from "react.reactive"
import {render} from "react-dom"


const searchUrl = q =>
  `https://api.github.com/search/repositories?q=${q}&sort=stars&order=desc`

const GithubSearch = R(({events}) => {
  const searchText =
    Kefir.fromEvents(events, "searchText:changed")
      .map(e => e.target.value)
      .merge(Kefir.fromEvents(events, "searchText:clear").map(() => ""))
      .merge(Kefir.constant(""))  // initial value
      .toProperty()

  const repos =
    searchText
      .debounce(300)
      .map(encodeURIComponent)
      .flatMapLatest(q => q.length < 3
        ? Kefir.constant({items: []})
        : Kefir.fromPromise(fetch(searchUrl(q)).then(req => req.json()))
      )
      .map(res => res.items.map(it => ({
        id: it.id,
        name: it.full_name,
        stars: it.stargazers_count
      })))

  return (
    <div>
      <h1>Github Repository search</h1>
      <R.input placeholder="Repository name"
               emits={{change: "searchText:changed"}}
               value={searchText} />
      <R.button emits={{click: "searchText:clear"}}
                disabled={searchText.map(t => t.length === 0)}>
        Reset
      </R.button>
      <R.ul>
        {repos.map(repos => repos.map(({id, name, stars}) =>
          <li key={id}>
            {name} (stars: {stars})
          </li>
        ))}
      </R.ul>
    </div>
  )
})

render(<GithubSearch />, document.getElementById("app"))

API

To use react.reactive, you must install it first with npm

npm i --save react.reactive

react.reactive works only with CommonJS compatible package managers (such as Webpack and Browserify).

Embedding observables to virtual dom

Observables can be embedded into VDOM by using react.reactive components. These VDOM components act like sinks/observers, causing the value of the embedded observable to be rendered every time it changes.

Components are lazy - they won't subscribe to the embedded observables until component gets mounted.

ATTENTION: Components subscribe only to observables that are in their properties or direct children.

import R from "react.reactive"
import {Observable} from "rx"

const Example = () => {
  const time = Observable.interval(1000)
    .startWith(null)
    .map(() => new Date().toTimeString())
    
  return (
    <div>
      <h1>Example</h1>
      <R.div>Time is {time}</R.div>
    </div>
  )
}

react.reactive contains components for all normal HTML tags. If you want to make your own custom component reactive, you can use factory function R. Components created with this method behave exactly like built-in react.reactive components

import R from "react.reactive"
import DatePicker from "react-date-picker"
import moment from "moment"
import {Observable} from "rx"


// make DatePicker reactive
const RDatePicker = R(DatePicker)

const Example = ({date}) => {
  const date = Observable.interval(1000)
    .startWith(null)
    .scan(m => moment(m).add(1, "day"), moment())
    .map(m => m.toDate())
    
  return (
    <div>
      <h1>Hello react.reactive!</h1>
      {/* now you can embed observables into it like R.div in prev example */}
      <RDatePicker date={date} />
    </div>
  )
}

Mounting / unmounting hooks

Because ref can't be used with React class components, reactive components signal their mounting and un-mounting with onMount and onUnmount lifecycle hooks.

Creating observables from DOM events

Emitting events

Reactive components can declare the events they send by using emits property. The property takes one JSON object that has event types as its keys and emitted event names as its values, e.g.

<R.button emits={{click: "my-btn-clicked"}}>My Button</R.button>
<R.input emits={{change: "event-name-can-be-anything"}} />

All React events (including onChange) are supported but they must be listened by using their lowercase name without on prefix: e.g. onChange => change and onKeyDown => keydown

Also custom event types work but they must be referenced by their original name, e.g.

const RDatePicker = R(DatePicker)
<RDatePicker emits={{onDateChange: "date-changed"}} />

Observing events

All events that are emitted from reactive components can be observed by any parent (or ancestor) component. When you make your component reactive with the R function, it adds an additional events property that is an event emitter / event target -- this means that you can use your observable library's utility functions to subscribe to the given event target fromEventTarget, fromEvent, etc.)

import {Observable} from "rx"
import R from "react.reactive"


const Counter = R(({events}) => {
  const inc$ = Observable.fromEvent(events, "inc-click").map(() => +1)
  const dec$ = Observable.fromEvent(events, "dec-click").map(() => -1)
  const counter$ =
    inc$.merge(dec$)
      .startWith(0)
      .scan((val, d) => val + d, 0)
      .shareReplay()

  return (
    <div>
      <R.h1>Counter {counter$}</R.h1>
      <R.button emits={{click: "inc-click"}}>++</R.button>
      <R.button emits={{click: "dec-click"}}>--</R.button>
    </div>
  )
})

Questions?

All questions are welcome. Please raise an issue or join the chat at Gitter!

License

MIT