hyperapp-render

Hyperapp Render

This library is allowing you to render Hyperapp views to an HTML string.

• User experience — Generate HTML on the server and send the markup down on the initial request for faster page loads. Built-in mounting feature in Hyperapp is allowing you to have a very performant first-load experience.
• Accessibility — Allow search engines to crawl your pages for SEO purposes.
• Testability — Check HTML validity and use snapshot testing to improve quality of your software.

Getting Started

Our first example is an interactive app from which you can generate an HTML markup. Go ahead and try it online.

import { h } from 'hyperapp'
import { renderToString } from 'hyperapp-render'

const state = {
  text: 'Hello'
}

const actions = {
  setText: text => ({ text })
}

const view = (state, actions) => (
  <main>
    <h1>{state.text.trim() === '' ? '👋' : state.text}</h1>
    <input value={state.text} oninput={e => actions.setText(e.target.value)} />
  </main>
)

const html = renderToString(view(state, actions))

console.log(html) // => <main><h1>Hello</h1><input value="Hello"/></main>

Looking for a boilerplate? Try Hyperapp Starter with pre-configured server-side rendering and many more.

Installation

Using npm:

npm install hyperapp-render --save

Or using a CDN like unpkg.com or jsDelivr with the following script tag:

<script src="https://unpkg.com/hyperapp-render"></script>

You can find the library in window.hyperappRender.

We support all ES5-compliant browsers, including Internet Explorer 9 and above, but depending on your target browsers you may need to include polyfills for Set and Map before any other code.

Usage

The library provides two functions which you can use depending on your needs or personal preferences:

import { renderToString, renderToStream } from 'hyperapp-render'

renderToString(<Component />)        // => <string>
renderToString(view(state, actions)) // => <string>
renderToString(view, state, actions) // => <string>

renderToStream(<Component />)        // => <stream.Readable> => <string>
renderToStream(view(state, actions)) // => <stream.Readable> => <string>
renderToStream(view, state, actions) // => <stream.Readable> => <string>

Note: renderToStream is available from Node.js environment only (v6 or newer).

Overview

You can use renderToString function to generate HTML on the server and send the markup down on the initial request for faster page loads and to allow search engines to crawl your pages for SEO purposes.

If you call hyperapp.app() on a node that already has this server-rendered markup, Hyperapp will preserve it and only attach event handlers, allowing you to have a very performant first-load experience.

The renderToStream function returns a Readable stream that outputs an HTML string. The HTML output by this stream is exactly equal to what renderToString would return. By using this function you can reduce TTFB and improve user experience even more.

Caveats

The library automatically escapes text content and attribute values of virtual DOM nodes to protect your application against XSS attacks. However, it is not safe to allow "user input" for node names or attribute keys:

const Node = 'div onclick="alert()"'
renderToString(<Node title="XSS">Hi</Node>)
// => <div onclick="alert()" title="XSS">Hi</div>

const attributes = { 'onclick="alert()" title': 'XSS' }
renderToString(<div {...attributes}>Hi</div>)
// => <div onclick="alert()" title="XSS">Hi</div>

const userInput = '<script>alert()</script>'
renderToString(<div title="XSS" innerHTML={userInput}>Hi</div>)
// => <div title="XSS"><script>alert()</script></div>

License

Hyperapp Render is MIT licensed. See LICENSE.

Changelog

[4.0.1] - 2022-06-29

• Allow empty string text nodes (#23).