Hyperapp Render
A Hyperapp higher-order app
that allows you to render 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, app } from 'hyperapp'
import { withRender } 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 main = withRender(app)(state, actions, view)
main.toString()
main.setText('World')
main.toString()
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/hyperapp-render.min.js"></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
,
Map
and
Object.assign
before any other code.
Usage
The library provides a few functions which you can use depending on your needs or personal preferences.
import { withRender, renderToString, renderToStream } from '@hyperapp/render'
const main = withRender(app)(state, actions, view, container)
main.toString()
renderToString(<Component />)
renderToString(view, state, actions)
main.toStream()
renderToStream(<Component />)
renderToStream(view, state, actions)
Note: functions toStream
and renderToStream
are available in
Node.js environment only (v6 or newer).
Overview
The library exposes three functions. The first of these is withRender
high-order function,
which adds the toString
action to be able to render your application to an HTML string at any given time.
This can be useful for server-side rendering or creating HTML snippets based on current application state.
import { h, app } from 'hyperapp'
import { withRender } from '@hyperapp/render'
const state = { name: 'World' }
const actions = { setName: name => ({ name }) }
const view = (state, actions) => <h1>Hello {state.name}</h1>
const main = withRender(app)(state, actions, view)
main.toString()
main.setName('Hyperapp')
main.toString()
The second renderToString
function generates HTML markup from any of your views without
app initialization. That could be useful to generate HTML markup from static views.
import { renderToString } from '@hyperapp/render'
const Component = ({ name }) => <h1>Hello {name}</h1>
renderToString(<Component name="World" />)
The last renderToStream
function and toStream
equivalent return a
Readable stream that outputs an HTML string.
The HTML output by this stream is exactly equal to what toString
or renderToString
would return.
They are designed for more performant server-side rendering and here are examples how they could be used
with Express or Koa:
app.get('/', (req, res) => {
res.write('<!doctype html><html><head>')
res.write('<title>Page</title>')
res.write('</head><body><div id="app">')
const main = withRender(app)(state, actions, view)
const stream = main.toStream()
stream.pipe(res, { end: false })
stream.on('end', () => {
res.write('</div></body></html>')
res.end()
})
})
app.get('/', (req, res) => {
res.write('<!doctype html>')
const stream = renderToStream(
<html>
<head><title>Page</title></head>
<body>
<div id="app">{view(state, actions)}</div>
</body>
</html>
)
stream.pipe(res)
})
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 because
the library does not reject injection attack on markup due to performance reasons.
See:
const Node = 'div onclick="alert()"'
renderToString(<Node title="XSS">Hi</Node>)
const attributes = { 'onclick="alert()" title': 'XSS' }
renderToString(<div {...attributes}>Hi</div>)
const userInput = '<script>alert()</script>'
renderToString(<div title="XSS" innerHTML={userInput}>Hi</div>)
License
Hyperapp Render is MIT licensed. See LICENSE.