typed-dom

typed-dom

A value-level and type-level DOM builder.

Visualize DOM structures and Assist DOM access using static types.

const dom: El<"article", HTMLElement, {
  style: El<"style", HTMLStyleElement, string>;
  title: El<"h1", HTMLHeadingElement, string>;
  content: El<"ul", HTMLUListElement, readonly El<"li", HTMLLIElement, string>[]>;
}>

Usage

Build a Typed-DOM component with styling. :scope selectors are replaced with :host, #<id>, or .<generated-id>.

import { HTML } from 'typed-dom';

const dom = HTML.article({
  style: HTML.style(':scope { color: red; }'),
  title: HTML.h1('Title'),
  content: HTML.ul([
    HTML.li('item'),
    HTML.li('item'),
  ]),
});

Then this component has the following readable static type generated by type inference.

const dom: El<"article", HTMLElement, {
  style: El<"style", HTMLStyleElement, string>;
  title: El<"h1", HTMLHeadingElement, string>;
  content: El<"ul", HTMLUListElement, readonly El<"li", HTMLLIElement, string>[]>;
}>

// Note: El type is defined as follows.
export interface El<
  T extends string = string,
  E extends Element = Element,
  C extends El.Children = El.Children,
  > {
  readonly tag: string;
  readonly element: E;
  get children(): El.Getter<C>;
  set children(children: El.Setter<C>);
}
export namespace El {
  export type Children =
    | Children.Void
    | Children.Text
    | Children.Node
    | Children.Array
    | Children.Struct;
  export namespace Children {
    export type Void = void;
    export type Text = string;
    export type Node = DocumentFragment;
    export type Array = readonly El[];
    export type Struct = { [field: string]: El; };
  }
  export type Getter<C extends El.Children> =
    C extends Node | readonly unknown[] ? C :
    C;
  export type Setter<C extends El.Children> =
    C extends Node | readonly unknown[] ? C :
    Partial<C>;
}

Using the static type, you can see the internal structure and can safely access to and manipulate it.

// Inspect
dom.element.outerHTML; // '<article class="RANDOM"><style>.RANDOM { color: red; }</style><h1>Title</h1><ul><li>item</li><li>item</li></ul></article>'
dom.children.title.element.outerHTML; // '<h1>Title</h1>'
dom.children.title.children; // 'Title'
dom.children.content.element.outerHTML; // '<ul><li>item</li><li>item</li></ul>'
dom.children.content.children[0].children; // 'item'

// Update
// - Text
dom.children.title.children = 'Text';
dom.children.title.element.outerHTML; // '<h1>Text</h1>'

// - Array
dom.children.content.children = [
  HTML.li('Array'),
];
dom.children.content.element.outerHTML; // '<ul><li>Array</li></ul>'

// - Struct
dom.children = {
  title: HTML.h1('Struct'),
};
dom.children.title.element.outerHTML; // '<h1>Struct</h1>'
dom.children.title = HTML.h1('title');
dom.children.title.element.outerHTML; // '<h1>title</h1>'

Examples

Typed-DOM supports custom elements but they are unrecommended since most of purposes of customizations can be realized by customizing proxies or APIs instead of elements.

DOM Components

Define composable DOM components.

import { Shadow, HTML, El } from 'typed-dom';

class Component implements El {
  private readonly dom = HTML.section({
    style: HTML.style(':scope { color: red; }'),
    content: HTML.ul([
      HTML.li('item'),
    ]),
  });
  public readonly tag = this.dom.tag;
  public readonly element = this.dom.element;
  public get children() {
    return this.dom.children.content.children;
  }
  public set children(children) {
    this.dom.children.content.children = children;
  }
}

Switch to shadow DOM. Access to elemets in shadow DOM is transparent.

class ShadowComponent implements El {
  private readonly dom = Shadow.section({
    style: HTML.style(':scope { color: red; }'),
    content: HTML.ul([
      HTML.li('item'),
    ]),
  });
  public readonly tag = this.dom.tag;
  public readonly element = this.dom.element;
  public get children() {
    return this.dom.children.content.children;
  }
  public set children(children) {
    this.dom.children.content.children = children;
  }
}

Define autonomous DOM components which orient choreography, not orchestration. This coroutine supports the actor model and the supervisor/worker pattern (using spica/supervisor).

import { Shadow, HTML, El } from 'typed-dom';
import { Coroutine } from 'spica/coroutine';

class Component extends Coroutine implements El {
  constructor() {
    super(async function* (this: Component) {
      let count = 0;
      this.children = `${count}`;
      while (true) {
        this.element.isConnected || await new Promise<unknown>(resolve =>
          this.element.addEventListener('connect', resolve, { once: true }));
        this.children = `${++count}`;
        yield;
      }
    }, { trigger: 'element', interval: 100 });
  }
  private readonly dom = Shadow.section({ onconnect: '' }, {
    style: HTML.style(':scope { color: red; }'),
    content: HTML.p(''),
  });
  public readonly tag = this.dom.tag;
  public readonly element = this.dom.element;
  public get children() {
    return this.dom.children.content.children;
  }
  public set children(children) {
    this.dom.children.content.children = children;
  }
}

i18n

Create a helper function of APIs for i18n.

import { HTML, El, html } from 'typed-dom';

const translator = i18next.createInstance({
  lng: 'en',
  resources: {
    en: {
      translation: {
        'Greeting': 'Hello, {{name}}.',
      },
    },
  },
});
interface TransDataMap {
  'Greeting': { name: string; };
}

function data
  <K extends keyof TransDataMap>
  (data: TransDataMap[K])
  : El.Factory<HTMLElementTagNameMap, K> {
  return (html, tag, _, children) =>
    html(tag, {
      onmutate: ev =>
        void translator.init((err, t) =>
          ev.currentTarget.textContent = err
            ? '{% Failed to initialize the translator. %}'
            : t(children, data) ?? `{% Failed to translate "${children}". %}`),
    });
}

const el = HTML.span('Greeting', data({ name: 'world' }));
assert(el.children === 'Hello, world.');
assert(el.element.textContent === 'Hello, world.');

Or

function intl
  <K extends keyof TransDataMap>
  (children: K, data: TransDataMap[K])
  : El.Factory<HTMLElementTagNameMap, El.Children.Void> {
  return (html, tag) => {
    const el = html(tag);
    translator.init((err, t) =>
      el.textContent = err
        ? '{% Failed to initialize the translator. %}'
        : t(children, data) ?? `{% Failed to translate "${children}". %}`);
    return el;
  };
}

const el = HTML.span(intl('Greeting', { name: 'world' }));
assert(el.children === undefined);
assert(el.element.textContent === 'Hello, world.');

APIs

HTML: { [tag]: (attrs?, children?, factory?) => El; (tag: string, ...): El; };

Create an HTML element proxy.

• attrs: Record<string, string | EventListener | null | undefined>
• children: undefined | string | El[] | Record<string, El> | DocumentFragment
• factory: () => Element

import { HTML, frag } from 'typed-dom';

HTML.p();
HTML.p('text');
HTML.p(frag(['a', html('br'), 'b']));
HTML.p([HTML.a()]);
HTML.p({ link: HTML.a() }]);
HTML.p({ id: 'id' });
HTML.p(() => document.createElement('p'));
HTML.p(() => document.querySelector('p'));
HTML('p', 'text');

SVG: { [tag]: (attrs?, children?, factory?) => El; (tag: string, ...): El; };

Create an SVG element proxy.

• attrs: Record<string, string | EventListener | null | undefined>
• children: undefined | string | El[] | Record<string, El> | DocumentFragment
• factory: () => Element

import { SVG } from 'typed-dom';

SVG.svg();

Shadow: { [tag]: (attrs?, children?, factory?) => El; (tag: string, ...): El; };

Create an HTML element proxy assigning the children to the own open shadow DOM.

• attrs: Record<string, string | EventListener | null | undefined>
• children: undefined | string | El[] | Record<string, El> | DocumentFragment
• factory: () => Element

import { Shadow } from 'typed-dom';

Shadow.section();

API

Create APIs

All the APIs creating an element can be recreated as follows:

import { API, NS, shadow, element } from 'typed-dom';

const html = element<HTMLElementTagNameMap>(document, NS.HTML);
const svg = element<SVGElementTagNameMap>(document, NS.SVG);

const Shadow = API<ShadowHostHTMLElementTagNameMap>(html, shadow);
const HTML = API<HTMLElementTagNameMap>(html);
const SVG = API<SVGElementTagNameMap>(svg);

A closed shadow DOM API can be created as follows:

const Shadow = API<ShadowHostHTMLElementTagNameMap>(html, el => shadow(el, { mode: 'closed' }));

Extend APIs

Custom elements can be created by extending ShadowHostHTMLElementTagNameMap, HTMLElementTagNameMap, or SVGElementTagNameMap interface.

import { Shadow, HTML } from 'typed-dom';

declare global {
  interface ShadowHostHTMLElementTagNameMap {
    'custom-tag': HTMLElement;
  }
  interface HTMLElementTagNameMap {
    'custom': HTMLElement;
  }
}

window.customElements.define('custom-tag', class extends HTMLElement { });
Shadow('custom-tag').element.outerHTML; // '<custom-tag></custom-tag>'
HTML('custom-tag').element.outerHTML; // '<custom-tag></custom-tag>'
HTML.custom().element.outerHTML; // '<custom></custom>'

However, since scoped custom elements don't inherit global custom elements you shouldn't extend the built-in interfaces such as HTMLElementTagNameMap. Instead, you should create new interfaces and new APIs to define custom elements.

import { API, shadow, html } from 'typed-dom';

interface CustomShadowHostElementTagNameMap extends ShadowHostHTMLElementTagNameMap {
  'custom-tag': HTMLElement;
}
interface CustomHTMLElementTagNameMap extends HTMLElementTagNameMap, CustomShadowHostElementTagNameMap {
  'custom': HTMLElement;
}

export const Shadow = API<CustomShadowHostElementTagNameMap>(html, shadow);
export const HTML = API<CustomHTMLElementTagNameMap>(html);

Ideally, you should define custom elements only as scoped custom elements.

import { API, NS, shadow, html as h, element } from 'typed-dom';

interface ShadowHostScopedCustomHTMLElementTagNameMap extends ShadowHostHTMLElementTagNameMap {
  'custom-tag': HTMLElement;
}
interface ScopedCustomHTMLElementTagNameMap extends HTMLElementTagNameMap, ShadowHostScopedCustomHTMLElementTagNameMap {
  'custom': HTMLElement;
}

// Note that the following code is based on the unstandardized APIs of scoped custom elements.
const registry = new CustomElementRegistry();
// This Host function creates a proxy and makes its shadow DOM in the base document (light DOM).
export const Host = API<ShadowHostHTMLElementTagNameMap>(h, el =>
  shadow(el, { mode: 'open', registry }));
// This html function creates a scoped custom element in a shadow DOM.
export const html = element<ScopedCustomHTMLElementTagNameMap>(
  shadow('body', { mode: 'open', registry }),
  NS.HTML);
// This HTML function creates a scoped custom element proxy in a shadow DOM.
export const HTML = API<ScopedCustomHTMLElementTagNameMap>(html);
// This Shadow function creates a scoped custom element proxy and makes its shadow DOM in a shadow DOM.
export const Shadow = API<ShadowHostScopedCustomHTMLElementTagNameMap>(html, shadow);

Others

• El
• NS
• Attrs
• Children
• Factory
• shadow
• frag
• html
• svg
• text
• define
• append
• prepend
• defrag
• listen
• once
• delegate
• bind
• currentTarget
• querySelector
• querySelectorAll

Events

These events are enabled only when an event listener is set using the Typed-DOM APIs.

mutate

The mutate event is dispatched when the children property value is changed.

connect

The connect event is dispatched when added to another proxy connected to the context object.

disconnect

The disconnect event is dispatched when removed from the parent proxy connected to the context object.

Dependencies

• unassert (in compiling source code)