Minimal view layer for creating declarative web user interfaces
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README.md

Superfine

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Superfine is a minimal view layer for creating declarative web user interfaces. Mix it with your favorite state container or use it standalone for maximum flexibility.

Installation

npm i superfine

Don't want to set up a build environment? Download Superfine from unpkg (or jsdelivr) and it will be globally available through the window.superfine object. Works in ES5-friendly browsers >=IE9.

<script src="https://unpkg.com/superfine"></script>

Usage

Here is the first example to get you started. Go ahead and try it online or find more examples here.

import { h, patch } from "superfine"

const view = count =>
  h("div", {}, [
    h("h1", {}, count),
    h("button", { onclick: () => render(count - 1) }, "-"),
    h("button", { onclick: () => render(count + 1) }, "+")
  ])

const app = (view, container, node) => state => {
  node = patch(node, view(state), container)
}

const render = app(view, document.body)

render(0)

Every time something needs to change in our application, we create a new virtual DOM using superfine.h, then patch the actual DOM with superfine.patch.

patch(lastNode, nextNode, container)

So, what's a virtual DOM? A virtual DOM is a description of what a DOM should look like using a tree of plain JavaScript objects called virtual nodes. By comparing the old and new virtual DOM we can update the parts of the DOM that actually changed instead of rendering the entire document from scratch.

The next example shows how to use HTML attributes to synchronize the text of an input with a heading element. Superfine nodes support HTML attributes, SVG attributes, DOM events, keys and lifecycle events.

import { h, patch } from "superfine"

const view = state =>
  h("div", {}, [
    h("h1", {}, state),
    h("input", {
      autofocus: true,
      type: "text",
      value: state,
      oninput: e => render(e.target.value)
    })
  ])

const app = (view, container, node) => state => {
  node = patch(node, view(state), container)
}

const render = app(view, document.body)

render("Hello!")

Recycling

Superfine can patch over your server-side rendered HTML to enable SEO optimizations and improve your sites time-to-interactive. All you need to is create a virtual DOM out of your container using superfine.recycle, then instead of throwing away the existing content, superfine.patch will turn it into an interactive application.

import { h, patch, recycle } from "superfine"

const container = document.body

let lastNode = patch(recycle(container), nextNode, container)

Styles

The style attribute expects a plain object rather than a string as in HTML. Each declaration consists of a style name property written in camelCase and a value. CSS variables are supported too.

import { h } from "hyperapp"

export const Jumbotron = text =>
  h(
    "div",
    {
      style: {
        color: "white",
        fontSize: "32px",
        textAlign: center,
        backgroundImage: `url(${imgUrl})`
      }
    },
    text
  )

Keys

Keys help identify nodes every time we update the DOM. By setting the key property on a virtual node, you declare that the node should correspond to a particular DOM element. This allow us to re-order the element into its new position, if the position changed, rather than risk destroying it. Keys must be unique among sibling-nodes.

import { h } from "superfine"

export const ImageGallery = images =>
  images.map(({ hash, url, description }) =>
    h("li", { key: hash }, [
      h("img", {
        src: url,
        alt: description
      })
    ])
  )

Top-Level Nodes

Keys are not registered on the top-level node of your view. If you are toggling the top-level view, and you must use keys, wrap them in an unchanging node.

Lifecycle Events

You can be notified when elements managed by the virtual DOM are created, updated or removed via lifecycle events. Use them for animation, wrapping third party libraries, cleaning up resources, etc.

oncreate

This event is fired after the element is created and attached to the DOM. Use it to manipulate the DOM node directly, make a network request, etc.

import { h } from "superfine"

export const Textbox = placeholder =>
  h("input", {
    type: "text",
    placeholder,
    oncreate: element => element.focus()
  })

onupdate

This event is fired every time we try to update the element attributes. Use the lastProps attributes inside the event handler to check if any attributes changed or not.

import { h } from "superfine"
import { RichEditor } from "richeditor"

export const Editor = value =>
  h("div", {
    key: "editor",
    oncreate: element => {
      element.editor = new RichEditor({ text: value })
    },
    onupdate: (element, lastProps) => {
      if (lastProps.value !== value) {
        element.editor.update({ text: value })
      }
    },
    ondestroy: element => {
      delete element.editor
    }
  })

onremove

This event is fired before the element is removed from the DOM. Use it to create slide/fade out animations. Call done inside the function to remove the element. This event is not called in its child elements. See ondestroy for that.

import { h } from "superfine"

export const MessageWithFadeout = message =>
  h(
    "div",
    {
      onremove: (element, done) => {
        element.classList.add("fade-out")
        setTimeout(done, 1000)
      }
    },
    [h("h1", {}, message)]
  )

ondestroy

This event is fired after the element has been removed from the DOM, either directly or as a result of a parent being removed. Use it for invalidating timers, canceling a network request, removing global events listeners, etc.

import { h } from "superfine"

export const Camera = onerror =>
  h("video", {
    poster: "loading.png",
    oncreate: element => {
      navigator.mediaDevices
        .getUserMedia({ video: true })
        .then(stream => (element.srcObject = stream))
        .catch(onerror)
    },
    ondestroy: element => element.srcObject.getTracks()[0].stop()
  })

JSX

JSX is an optional language syntax extension that lets you write HTML tags interspersed with JavaScript. To use JSX install the JSX transform plugin and add the pragma option to your .babelrc file (don't have one? create it in the root of your project).

{
  "plugins": [
    [
      "transform-react-jsx",
      {
        "pragma": "h"
      }
    ]
  ]
}

Functional Components

A functional component is a function that returns a virtual node. Unlike React, Inferno, etc., Superfine components are stateless — class based components can't be created. Everything the component needs to work must be passed on via the props argument, which consists of the component attributes and children.

import { h, patch } from "superfine"

const ClickMe = props => (
  <a href={props.url}>
    <h1>{props.children}</h1>
  </a>
)

let lastNode = patch(
  null,
  <ClickMe url="/">Click Here!</ClickMe>,
  document.body
)

License

Superfine is MIT licensed. See LICENSE.