hyperhtml

hyperHTML

A Fast & Light Virtual DOM Alternative

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The easiest way to describe hyperHTML is through an example.

// this is React's first tick example
// https://facebook.github.io/react/docs/state-and-lifecycle.html
function tick() {
  const element = (
    <div>
      <h1>Hello, world!</h1>
      <h2>It is {new Date().toLocaleTimeString()}.</h2>
    </div>
  );
  ReactDOM.render(
    element,
    document.getElementById('root')
  );
}
setInterval(tick, 1000);

// this is hyperHTML
function tick(render) {
  render`
    <div>
      <h1>Hello, world!</h1>
      <h2>It is ${new Date().toLocaleTimeString()}.</h2>
    </div>
  `;
}
setInterval(tick, 1000,
  hyperHTML.bind(document.getElementById('root'))
);

Features

• Zero dependencies and fits in less than a kilobyte (minzipped)
• Uses directly native DOM instead of inventing new syntax/APIs, DOM diffing, or virtual DOM
• Designed for template literals, a templating feature built in to JS
• Compatible with vanilla DOM elements and vanilla JS data structures ^{_{(actually, this is just a 100% vanilla JS utility, that's why is most likely the fastest and also the smaller. I fell like I'm writing Assembly these days ...)}}
• Compatible 1:1 with Babel transpiled output, hence compatible with every browser you can think of

... wait, WAT?

ES6 Template literals come with a special feature that is not commonly used: prefixed transformers.

Using such feature to map a template string to a generic DOM node, makes it possible to automatically target and update only the differences between two template invokes and with no innerHTML involved.

Following an example:

function update(render, state) {
  return render `
  <article data-magic=${state.magic}>
    <h3>${state.title}</h3>
    List of ${state.paragraphs.length} paragraphs:
    <ul>${
      state.paragraphs
        .map(p => `<li>${p.title}</li>`)
        .join('')
    }</ul>
  </article>
  `;
}

update(
  hyperHTML.bind(articleElement),
  {
    title: 'True story',
    paragraphs: [
      {title: 'touching'},
      {title: 'incredible'},
      {title: 'doge'}
    ]
  }
);

Since most of the time templates are 70% static text and 30% or less dynamic, hyperHTML passes through the resulting string only once, finds all attributes and content that is dynamic, and maps it 1:1 to the node to make updates as cheap as possible for both node attributes and node content.

Usage

You have a hyperHTML function that is suitable for parsing template literals but it needs a DOM node context to operate.

If you want to render many times the same template for a specific node, bind it once and boost up performance for free. No new nodes, or innerHTML, will be ever used in such case: safe listeners, faster DOM.

F.A.Q. and Caveats

• how can I differentiate between textContent only and HTML or DOM nodes? If there's any space or char around the value, that'd always be a textContent. Other cases accept DOM nodes as well as html, but it's obviously slightly slower. As summary: render`<p>This is: ${'text'}</p>`; for text, and render`<p>${'html' || node}</p>`; for everything else.

• can I use different renders for a single node? Sure thing. However, the best performance gain is reached with nodes that always use the same template string. If you have a very unpredictable conditional template, you might want to create two different nodes and apply hyperHTML with the same template for both of them, swapping them when necessary. In every other case, the new template will create new content and map it once per change.

Compatibility

If your string literals are transpiled, this project should be compatible with every single browser, old or new.

If you don't transpile string literals, check the test page and wait 'till it's green.

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(C) 2017 Andrea Giammarchi - MIT Style License