A tiny (511 byte) virtual DOM template engine for embedded projects

IE / Edge	Firefox	Chrome	Safari	Opera	iOS Safari	Chrome for Android
Edge 14+	45+	49+	10+	37+	10.2+	55+

.dom borrows some concepts from React.js (such as the re-usable Components and the Virtual DOM) and tries to replicate them with the smallest possible footprint, exploiting the ES6 javascript features.

Why? Because with such library you can create powerful GUIs in tight space environments, such as IoT devices, where saving even an extra byte actually matters!

• Tiny by design : The library should never exceed the 512 bytes in size. The goal is not to have yet another template engine, but to have as many features as possible in 512 bytes. If a new feature is needed, an other must be sacraficed or the scope must be reduced.

• Built for the future : The library is heavily exploiting the ES6 specifications, meaning that it's not supported by older browsers. Currently it's supported by the 70% of the browsers in the market, but expect this to be 90% within the next year.

• Declarative : Describe your HTML DOM in a structured, natural manner, helping you create powerful yet readable user interfaces.

• Component-Oriented : Just like React.js, .dom promotes the use of functional components.

• "Write less" accelerators : The library API is designed specifically to have short function names and accelerators, allowing you to describe your views with less code.

For minimum footprint, include dotdom.min.js.gz (511b) to your project.

<script src="dotdom.min.js.gz" />

Alternatively you can just include the minified version of the library directly before your script. Just copy-paste the minified code.

If you already know React.js, the following examples can help you understand how the .dom primitives relate to React.

Rendering a very simple DOM structure.

ReactDOM.render(
  React.createElement('div', null, 'Hello world'),
  document.body
);

R(
  H('div', 'Hello world'),
  document.body
)

Creating a component on which you can pass properties.

function Hello(props) {
    return React.createElement(
      'div', null, `Hello ${props.toWhat}`
    );
  }
ReactDOM.render(
React.createElement(
Hello, {toWhat: 'World'}, null
),
document.body
);

function Hello(props) {
  return H('div', `Hello ${props.toWhat}`);
}

R(
  H(Hello, {toWhat: 'World'}),
  document.body
)

</td>

Creating components that can maintain their own state.

class Clickable extends React.Component {
  constructor() {
    super(...arguments);
    this.state = {
      clicks: 0
    };
  }
render() {
const {clicks} = this.state;
return React.createElement(
  'button', {
    onClick() {
      this.setState({clicks: clicks+1})
    }
  }, `Clicked ${clicks} times`
);

}
}
ReactDOM.render(
React.createElement('div', null,
React.createElement(Clickable, null, null),
React.createElement(Clickable, null, null)
),
document.body
);

function Clickable(props, state, setState) {
  const {clicks=0} = state;

  return H('button',
    {
      onclick() {
        setState({clicks: clicks+1})
      }
    },
    `Clicked ${clicks} times`
  );
}

R(
  H('div',
    H(Clickable),
    H(Clickable)
  ),
  document.body
)

</td>

R( H('div', 'Hello'), document.body )

Renders the given VNode tree to the given DOM element. Further updates from stateful components will only occur on their immediate children.

H( 'tag' )
H( 'tag', {prop: "value"})
H( 'tag', H( 'child' ))
H( 'tag', {prop: "value"}, H( 'child' ))
H( Component, {prop: "value"} )

Creates a VNode element. If a string is passed as the first argument, it will create a HTML element. If a function is given, it will create a stateful component.

Properties and children are optional and they can be omitted.

Instead of a tag name you can provide a function that returns a Virtual DOM according to some higher-level logic. Such function have the following signature:

const Component = (props, state, setState) {

  // Return your Virtual DOM
  return div( ... )
}

The props property contains the properties object as given when the component was created.

The state is initialized to an empty object {} and it's updated by calling the setState({ newState }) method. The latter will also trigger an update to the component and it's children.

You can also assign properties to the state object directly if you don't want to cause an update.

const {div, span, a} = H;

div( 'hello', span( 'world' ) )
div( 'click', a({href: '#'}, 'Here'), 'to continue')

A shorthand function can be extracted as a property from the H function. Such shorthands behave exactly like H, but with the tag name already populated.

It's recommended to use a deconstructuring assignment in the beginning of your script in order to help javascript minifiers further optimize the result:

const {div, span, a, button} = H;

const {h1, span, p} = H;

h1.short( 'short header', span.strong( 'strong text' ) )
button.primary({onclick: handleClick}, 'Primary Action')
p.bold.italic( twitterPost )

Instead of providing the className as a property, you can use the .className shorthand in combination with the shorthand tag methods.

This is the same as calling div({className: 'className'}) and the function interface is exactly the same as above.

Note: You can add more than one class by concatenating more than one .class to the tag. For example: div.foo.bar is the same as div({className: 'foo bar'}).

• You cannot trigger an update with a property removal. You must set the new property to an empty value instead. For example:

  // Wrong
  R(div({className: 'foo'}), document.body);
  R(div({}), document.body);
  
  // Correct
  R(div({className: 'foo'}), document.body);
  R(div({className: ''}), document.body);

Are you interested in contributing to .dom? You are more than welcome! Just be sure to follow the guidelines:

1. Install a local development environment (you will need node.js 6.x or later)

npm install

2. Always run the following when you think you are ready for a pull request:

npm test && npm run build && ls -l dotdom.min.js.gz

3. If tests pass and the size of dotdom.min.js.gz is smaller than or equal to 512 bytes, create a pull request. Otherwise reduce your scope or think of another implementation in order to bring it back down to 512 bytes.

4. Make sure to properly comments your code, since you will most probably have to do some extreme javascript hacking. The gudeliens are the following:

/**
 * Functions are commented as JSDoc blocks
 *
 * @param {VNode|Array<VNode>} vnodes - The node on an array of nodes to render
 * ...
 */
global.R = render = (
  vnodes,                                                           // Flat-code comments start on column 70 and
  dom,                                                              // wrap after column 120.

  /* Logical separations can be commented like this */

  ...