Evolui NPM | npm.io

evolui

A tiny reactive user interface library.

Evolui magically understands Observable and Promises and takes care of refreshing your UI when they emit new values. You can only care about where the data should be displayed.

Install

npm install evolui rxjs

Examples

All examples Demo — see code
Simple Animation Demo — see code
Complex Animation Demo — see code
Animated Pinterest Like Grid Demo — see code

To jump to the code, visite the example folder.

Promises

import html, { render } from 'evolui'
const delay = ms => new Promise(resolve => setTimeout(resolve, ms))

render(
  html`
    <p>
      Hello, ${delay(1000).then(() => 'World!')}
    </p>
  `,
  document.querySelector('#mount')
)

Promise demo

Observables

import html, { render } from 'evolui'
import { interval } from 'rxjs'
import { take, map } from 'rxjs/operators'

render(
  html`
    <p>
      Hello, ${interval(1000).pipe(
        take(4),
        map(index => ['.', '..', '...', 'World!'][index])
      )}
    </p>
  `,
  document.querySelector('#mount')
)

Observable demo

Concept

The main goal of evolui is to make dealing with observables as easy as dealing with regular values.

Observables are a great way to represent values that change over time. The hard part though is combining them. This is where evolui comes in handy. It understands any combination of Arrays, Promises and Observables, so you never have to worry about the way you should combine them before putting them inside your template.

import html from 'evolui'
import { from } from 'rxjs'
import { startWith } from 'rxjs/operators'

const getCharacterName = id =>
  fetch(`https://swapi.co/api/people/${id}`)
    .then(res => res.json())
    .then(character => character.name)

html`
  <div>
    ${'' /* this will return an array of observables. */}
    ${'' /* Don't panic! evolui understands that as well */}
    ${[1, 2, 3].map(
      id => html`
        <h1>
          ${from(getCharacterName(id)).pipe(startWith('Loading...'))}
        </h1>
      `
    )}
  </div>
`

list demo

Components

Evolui lets you organize your code in components.

Components are defined as a simple function of Observable Props -> Observable VirtualDOM:

import html, { createState, render } from 'evolui'
import { map } from 'rxjs/operators'

const Button = props$ =>
  props$.pipe(
    map(
      ({ text, onClick }) => html`
        <button class="Button" onClick=${onClick}>
          ${text}
        </button>
      `
    )
  )

const App = () => {
  const state = createState({ count: 0 })

  return html`
    <div>
      <${Button}
        text="-"
        onClick=${() => state.count.set(c => c - 1)}
      />

      count: ${state.count}

      <${Button}
        text="+"
        onClick=${() => state.count.set(c => c + 1)}
      />
    </div>
  `
}

render(html`<${App} />`, document.querySelector('#mount'))

children

Components can have children 👍

import html, { render } from 'evolui'
import { map } from 'rxjs/operators'

const CrazyLayout = map(({ children }) => html`<div>${children}</div>`)

render(
  html`
    <${CrazyLayout}>
      <p>I'm the content</p>
    </${CrazyLayout}>
  `,
  document.querySelector('#mount')
)

Animations

Evolui exports a spring animation helper called ease.

ease: (stiffness: number, damping: number) => number => Observable<number>

You just have to pipe any of your observables to switchMap(ease(<stiffness>, <damping>)) to make it animated.

import html, { render, ease } from 'evolui'
import { fromEvent } from 'rxjs'
import { switchMap, map, startWith } from 'rxjs/operators'

const position$ = fromEvent(window, 'click').pipe(
  map(() => ({ x: e.clientX, y: e.clientY })),
  startWith({ x: 0, y: 0 })
)

render(
  html`
    <div
      class="circle"
      style="transform: translate(
        ${position$.pipe(map(p => p.x), switchMap(ease(120, 18)))}px,
        ${position$.pipe(map(p => p.y), switchMap(ease(120, 18)))}px
      );"
    />
  `,
  document.querySelector('#mount')
)

animation demo

API

text :: TemplateLiteral -> Observable String

import { text } from 'evolui'

const style$ = text`
  position: absolute;
  transform: translate(${x$}px, ${y$}px);
`

html :: TemplateLiteral -> Observable VirtualDOM

import html from 'evolui'

const App = () => html`
  <div style="${style$};" />
`

render :: Observable VirtualDOM -> DOMNode -> ()

import { render } from 'evolui'

render(html`<${App} />`, document.querySelector('#mount'))

ease :: (Number, Number) -> Observable Number -> Observable Number

import { ease } from 'evolui'
import { interval } from 'rxjs'
import { switchMap } from 'rxjs/operators'

interval(1000).pipe(
  switchMap(ease(120, 20)),
  subscribe(x => console.log(x)) // every values will be interpolated
)

createState :: Object -> State

Create an object of mutable reactive values.

Each key on your initial state will be transformed into a stream, with a special set method on it. set can take either a value or a mapper function.

import html, { createState, render } from 'evolui'

const state = createState({ count: 0 })

console.log(state.count)
// => Observable.of(0)

const reset = () => state.count.set(0)
const add1 = () => state.count.set(c => c + 1)

render(
  html`
    <div>
      count: ${state.count}
      <button onClick=${reset}>reset</button>
      <button onClick=${add1}>+</button>
    </div>
  `,
  document.querySelector('#mount')
)

all :: Observable a -> Observable a

import { all } from 'evolui'

const z$ = all([x$, y$]).map(([x, y]) => x + y)

Lifecycle

mount — after the element as been rendered
update — after the dom element as been update
unmount — before the dom element is removed from the dom

html`
  <div
    mount="${el => console.log('mounted!', el)}"
    update="${el => console.log('updated', el)}"
    unmount="${el => console.log('will unmount!', el)}" />
`