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astro/packages/integrations/lit/server.js
Elliott Marquez 0db2204153
[Lit] Fix hydration not having the same reactive values as server (#6080)
* Fix lit hydration not having the same reactive values

* add changeset

* add clientEntrypoint to package exports

* update tests

* add changeset

* only add defer-hydration when strictly necessary

* remove second changest

* fix test typos
2023-02-01 08:18:37 -05:00

107 lines
2.9 KiB
JavaScript

import './server-shim.js';
import '@lit-labs/ssr/lib/render-lit-html.js';
import { LitElementRenderer } from '@lit-labs/ssr/lib/lit-element-renderer.js';
import * as parse5 from 'parse5';
function isCustomElementTag(name) {
return typeof name === 'string' && /-/.test(name);
}
function getCustomElementConstructor(name) {
if (typeof customElements !== 'undefined' && isCustomElementTag(name)) {
return customElements.get(name) || null;
} else if (typeof name === 'function') {
return name;
}
return null;
}
async function isLitElement(Component) {
const Ctr = getCustomElementConstructor(Component);
return !!(Ctr && Ctr._$litElement$);
}
async function check(Component, _props, _children) {
// Lit doesn't support getting a tagName from a Constructor at this time.
// So this must be a string at the moment.
return !!(await isLitElement(Component));
}
function* render(Component, attrs, slots) {
let tagName = Component;
if (typeof tagName !== 'string') {
tagName = Component[Symbol.for('tagName')];
}
const instance = new LitElementRenderer(tagName);
// LitElementRenderer creates a new element instance, so copy over.
const Ctr = getCustomElementConstructor(tagName);
let shouldDeferHydration = false;
if (attrs) {
for (let [name, value] of Object.entries(attrs)) {
const isReactiveProperty = name in Ctr.prototype;
const isReflectedReactiveProperty = Ctr.elementProperties.get(name)?.reflect;
// Only defer hydration if we are setting a reactive property that cannot
// be reflected / serialized as a property.
shouldDeferHydration ||= isReactiveProperty && !isReflectedReactiveProperty;
if (isReactiveProperty) {
instance.setProperty(name, value);
} else {
instance.setAttribute(name, value);
}
}
}
instance.connectedCallback();
yield `<${tagName}${shouldDeferHydration ? ' defer-hydration' : ''}`;
yield* instance.renderAttributes();
yield `>`;
const shadowContents = instance.renderShadow({});
if (shadowContents !== undefined) {
yield '<template shadowroot="open">';
yield* shadowContents;
yield '</template>';
}
if (slots) {
for (let [slot, value = ''] of Object.entries(slots)) {
if (slot !== 'default' && value) {
// Parse the value as a concatenated string
const fragment = parse5.parseFragment(`${value}`);
// Add the missing slot attribute to child Element nodes
for (const node of fragment.childNodes) {
if (node.tagName && !node.attrs.some(({ name }) => name === 'slot')) {
node.attrs.push({ name: 'slot', value: slot });
}
}
value = parse5.serialize(fragment);
}
yield value;
}
}
yield `</${tagName}>`;
}
async function renderToStaticMarkup(Component, props, slots) {
let tagName = Component;
let out = '';
for (let chunk of render(tagName, props, slots)) {
out += chunk;
}
return {
html: out,
};
}
export default {
check,
renderToStaticMarkup,
};