amp-js

A virtual DOM alternative to build declarative and reactive UI using template literal tags.

• Highly Flexible: Use expressive JavaScript templates that can render anything to HTML. Set properties and event listeners directly from the template.
• Extremely Performant: Using the latest generation of rendering techniques, it easily outperforms contemporary VirtualDOM-based rendering as used in modern frontend frameworks.
• Lightweight: ~2.6kb total size.
• Extensible: Create components, pass props, handle lifecycle events and efficiently update the DOM by using HTML templating.

Overview

amp-js lets you write HTML templates in JavaScript with template literals.

import { html, render } from '@arish-shah/amp';

// This is an amp template function. It returns an amp template.
const helloTemplate = (name) => html` <div>Hello ${name}!</div> `;

// This renders <div>Hello Ben!</div> to the document body
render(helloTemplate('Ben'), document.body);

// This updates to <div>Hello Rey!</div>, but only updates the ${name} part
render(helloTemplate('Rey'), document.body);

Core API

Function render(<any>, Node)

The render function will render any type of object into the content of an HTML Node, usually the document body, a container element, or a shadowRoot.

The first argument is the object that will be rendered. It can be one of the following:

• A TemplateResult (returned by the html tag)
• A string, number, or boolean
• An HTML DOM Node
• An Array-like object

Any other object is coerced to a String before being rendered.

The second argument is the Node that the object will be rendered into. The previous content of the Node will be removed.

Function html

The html is a JavaScript template tag that allows creation of flexible templates which will be interpreted as HTML. To use the tag, prepend it to any JavaScript template literal.

const template = () => html` <p>Hello World</p> `;

The contents of the template will be parsed as HTML. The flexibility comes from interpreted values that can be inserted into these templates.

const template = (name) => html` <p>Hello ${name}!</p> `;

These interpreted values can in turn be any kind of object that amp-js can render, including nested templates and arrays.

Extended Usage

Function component

The component function can be used to create custom reusable components. It is provided with the default export.

• Each component has a first argument id, which helps amp-js locate its usage.
• The second parameter is a description object that contains an optional dynamic data object, methods to mutate them, props passed to the component, templates used inside it and the template itself. amp-js automatically binds this to the data, so they can be effectively changed causing a rerender.
• Each component should have a template function which gets called upon component creation.
• Execution of this function returns another function that can be called repeatedly to efficiently update the content.
• Changing the data members inside a component causes it to update automatically.

const Hello = Amp.component('amp-hello', {
  template() {
    return html`<h1>Hello World</h1>`;
  }
});

Hello.generate();

The component can be consumed in HTML as such:

<amp-hello></amp-hello>

---

For a more complex component,

import Amp, { html } from 'https://unpkg.com/@arish-shah/amp';

const Counter = Amp.component('amp-counter', {
  data: {
    count: 0,
    step: 1
  },
  onmount() {
    this.count = +this.attr('start');
    this.step = +this.attr('step');
  },
  methods: {
    decrement() {
      this.count -= this.step;
    },
    increment() {
      this.count += this.step;
    }
  },
  template() {
    return html`
      <div class="counter">
        <button @click=${this.decrement}>Decrement</button>
        <span>${this.count}</span>
        <button @click=${this.increment}>Increment</button>
      </div>
    `;
  }
});

Counter.generate();

We can now create multiple app-counter component in our HTML, passing start and step as props:

<!-- Starts counter with 5 and increments/decrements by 5 -->
<app-counter start="5" step="5"></app-counter>

<!-- Starts counter with 8 and increments/decrements by 3 -->
<app-counter start="8" step="3"></app-counter>

Attributes

1. Dynamic attributes

The html tag can also be used to set attributes on nodes. To set an attribute, assign the value of the attribute with an interpreted value. amp-js requires that you omit the surrounding " when setting attributes.

const template = (source) => html` <img src=${source} /> `;

// Composite attribute
const template = (classString) => html`
  <div class=${`red ${classString}`}></div>
`;

2. Boolean attributes

You can set boolean attributes by prefixing the attribute name with ?

const template = (secret) => html` <p ?hidden=${secret}></p> `;

3. Properties

You can set properties on elements by prefixing an attribute name with .

const template = (user) => html` <user-panel .user=${user}></user-panel> `;

4. Event handlers

You can attach event handlers by prefixing an attribute name with @

const handleClick = () => {
  alert('clicked the button');
};

const template = () => html` <button @click=${handleClick}></button> `;

Installation

npm

amp-js is distributed on npm, in the @arish-shah/amp package.

$ npm install @arish-shah/amp

unpkg.com

You can also load amp-js directly from the unpkg.com CDN:

import Amp, { html, render } from 'https://unpkg.com/@arish-shah/amp';

Or, you can create an index.html file and include amp-js with:

<!-- development version -->
<script type="module">
  import Amp, {
    html,
    render
  } from 'https://unpkg.com/@arish-shah/amp@latest/amp.js';
</script>

<!-- production version -->
<script type="module">
  import Amp, {
    html,
    render
  } from 'https://unpkg.com/@arish-shah/amp@latest/amp.min.js';
</script>

License

MIT License