Doremifa

Reactive view library based on tagged template literals. It is special compared to other similar libraries in that it implements it's own XHTML/HTML parser.

The main features are

• Reactive template literals where only changed parts are re-rendered
• Event handler support
• SVG support
• Has reactive global state, which can be used (not mandatory)
• Router baked in (or you can use your own)

A simple TypeScript example

import * as Doremifa from 'doremifa'

const html = Doremifa.html;
const setState = Doremifa.setState

Doremifa.setState({
  time:(new Date).toTimeString(),
})
Doremifa.mount(document.body, state => html`<div>Hello World! ${state.time}</div>`)
setInterval( _ => { setState({time:(new Date).toTimeString()})},1000)

Hello World in CodePen Router Example in CodePen

Usage and Install

npm i doremifa

And then

import { mount, router, getState, setState, html, drmfComponent, drmfTemplate } from 'doremifa';
// or
import * as Doremifa from './index';

html -literal

To construct a Template you can write JavaScript template literal

  html`<div>${"Hello World"}</div>`

Doremifa.mount

Mount render function to some element

Doremifa.mount(document.body, state => html`<div>Hello World!</div>`)

Functions

Any function which returns drmfTemplate can be used as a component

function message(txt) {
  return html`<div>${txt}</div>`
}
const example = html`<div>${message(txt)}</div>`

Objects

Objects which implement render() -function and inherit from drmfComponent can be used as part of templates.

class Hello extends drmfComponent {
  render() {
    return html`<div>Hello World </div>`
  }
}
const obj = new Hello(); // create and re-use if needed
Doremifa.mount(document.body, state => html`<div>${obj}</div>`)

Attributes can be set by value without quotes

const style='color:blue;'
html`<div style=${style}/>`

Events

Event handlers get two params:

• e the HTML event
• tpl the drmfTemplate -object which can old ID or list values

html`<button onclick=${(e, tpl) => {
  // tpl holds the template object
}}>Click me!</button>`

References

References are collected from templates to two colletions:

• ids holds elements having "id" attribute set
• list holds elements having list="something" set

The are also available to event handlers.

html`<div>
  <input id="name" />
  <div list="divs" />
  <div list="divs" />
  <button onclick=${(e, tpl) => {
    alert(tpl.ids.name)           // value of input 
    alert(tpl.list.divs.length)   // 2
}}>Click me!</button>
</div>`

Event after template is assigned

Sometimes you want to manipulate DOM after the template has been rendered

html`<div></div>`.onReady( tpl => {
  // tpl.ids
  // tpl.list
})

Custom Tags?

There are no custom tags, just functions or objects.

State and rendering

The application has a global state which is accessed using

• getState()
• setState({...})

When state is updated, rendering is triggered and all parts of the application are processed. This should be extremely fast, since templates are cached and only changed parts are updated.

Promises inside View?

No. Promises are not part of view tree. Just update state and view changes reactively.

Doremifa.router

Build -in router router uses window.location.hash and acceptse links in format

  <a href="#page1/param1/value1/param2/value2">Link to page 1</a>
  <a href="#page2/param1/value1/param2/value2">Link to page 2</a>

Then you can define router anywhere in templates like

html`<div>  
    ${Doremifa.router({
        page1 : (state) => html`page1`,
        page2 : (state) => html`page2`,
      })
    </div>`

The router component gets the state having following variables set

{
  "page": "page2",
  "params": {
    param1 : value1,
    param2 : value2
  }
}

Other Similar libraries

• hyperHTML
• lit-html
• YallaJS

Tutorials on similar subjects

• https://www.twilio.com/blog/2018/05/building-a-chat-with-twilio-lit-html-parcel-and-typescript.html
• https://itnext.io/a-tiny-disastrous-ecmascript-change-fadc05c83e69

License

MIT.