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Preact DOM render using undom
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// src/app/preactDomRenderer.js | |
import { h, render } from 'preact'; | |
import undom from 'undom'; | |
const VOID_ELEMENTS = [ | |
'area', | |
'base', | |
'br', | |
'col', | |
'embed', | |
'hr', | |
'img', | |
'input', | |
'link', | |
'meta', | |
'param', | |
'source', | |
'track', | |
'wbr', | |
]; | |
const ESC = { | |
'&': 'amp', | |
'<': 'lt', | |
'>': 'gt', | |
'"': 'quot', | |
"'": 'apos', | |
}; | |
const enc = s => s.replace(/[&'"<>]/g, a => `&${ESC[a]};`); | |
const attr = (a) => { | |
if (a.name === 'class' && a.value === '') { | |
return ''; | |
} | |
return ` ${a.name.replace(/^html/, '')}${a.value === 'true' || a.value === '' ? '' : `="${enc(a.value)}"`}`; | |
}; | |
const serializeHtml = (el) => { | |
const { nodeType, nodeName, textContent, attributes, childNodes, innerHTML } = el; | |
const normalizedNodeName = nodeName.toLowerCase(); | |
if (nodeType === 3) { | |
return enc(textContent); | |
} | |
const start = `<${normalizedNodeName}${attributes.map(attr).join('')}`; | |
if (VOID_ELEMENTS.includes(normalizedNodeName)) { | |
return `${start} />`; | |
} | |
return `${start}>${innerHTML || childNodes.map(serializeHtml).join('')}</${normalizedNodeName}>`; | |
}; | |
let doc; | |
const preactDomRenderer = () => { | |
if (!doc) { | |
doc = undom(); | |
Object.assign(global, doc.defaultView); | |
} | |
let root; | |
const parent = doc.createElement('x-root'); | |
doc.body.appendChild(parent); | |
const renderer = { | |
render: (jsx) => { | |
root = render(jsx, parent, root); | |
return renderer; | |
}, | |
html: () => serializeHtml(root), | |
tearDown: () => render(<nothing />, parent, root).remove(), | |
}; | |
return renderer; | |
}; | |
export default preactDomRenderer; |
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