@chialab/dna

DNA • Progressive Web Components

Features

DNA aims to unleash the true power of Custom Elements through a declarative definition API, with builtin elements extension support and a simpler composition mechanism (yes, it does not use ShadowDOM).

Customized built-in elements

DNA simplifies and encourages the use of customized built-in elements, which inherit methods and properties from standard HTML, preserving usability and accessibility features.

Properties, states and attributes

DNA offers @property and @state decorators for adding reactivity to a component's class fields, ensuring that any changes are reflected in the component's template. These properties and states can be monitored, synchronized with attributes, and trigger change events.

Listeners and async events

DNA uses event delegation for listening to events from a component's elements or slotted contents, offering the @listen decorator to streamline the process. Events can be asynchronous and dispatched from the component's class.

Slots

DNA uses Quantum instead of ShadowDOM to render slotted children, simplifying the usage of custom elements inside forms and providing a more flexible management of slotted contents. Unlike ShadowDOM, Quantum also works for built-in elements, allowing you to use even inside buttons.

Get the library

Usage via unpkg.com as ES6 module:

import { Component, define, html, ... } from 'https://unpkg.com/@chialab/dna?module';

Or install via NPM:

npm i @chialab/dna

yarn add @chialab/dna

Define a Component

import { Component, customElement, listen, property } from '@chialab/dna';

@customElement('hello-world')
class HelloWorld extends Component {
    // define an observed property
    @property() name: string = '';

    render() {
        return (
            <>
                <input
                    name="firstName"
                    value={this.name}
                />
                <h1>Hello {this.name || 'World'}!</h1>
            </>
        );
    }

    // delegate an event
    @listen('change', 'input[name="firstName"]')
    private onChange(event: Event, target: HTMLInputElement) {
        this.name = target.value;
    }
}

Then use the element in your HTML:

<hello-world></hello-world>

Development

Build the project

Install the dependencies and run the build script:

yarn install

yarn build

This will generate the bundles in the dist folder, as well as the declaration files.

Test the project

Run the test script:

yarn test

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License

DNA is released under the MIT license.

Changelog

4.0.0-alpha.0

Major Changes

• 9bac484: Remove support for node environment.
• 02d314e: Use quantum to handle component slotted children in light DOM.
• 02d314e: Expose $await and $pipe directives to treat promises and observables.