astro/packages/integrations/lit/src/client.ts
Elliott Marquez ec38a8921f
[Lit] add client:only functionality to Lit integration (#6111)
* [Lit] add `client:only` functionality to Lit integration

* add changeset

* update lit changeset to minor
2023-02-06 20:01:21 -05:00

72 lines
2.5 KiB
TypeScript

/**
* Adds the appropriate slot attribute to each top-level node in the given HTML
* string.
*
* @example
* addSlotAttrsToHtmlString('foo', '<div>bar</div><div>baz</div>');
* // '<div slot="foo">bar</div><div slot="foo">baz</div>'
*
* @param slotName Name of slot to apply to HTML string.
* @param html Stringified HTML that should be projected into the given slotname.
* @returns A stringified HTML string with the slot attribute applied to each top-level node.
*/
const addSlotAttrsToHtmlString = (slotName: string, html: string) => {
const templ = document.createElement('template');
templ.innerHTML = html;
Array.from(templ.content.children).forEach((node) => {
node.setAttribute('slot', slotName);
});
return templ.innerHTML;
};
export default (element: HTMLElement) =>
async (
Component: any,
props: Record<string, any>,
{ default: defaultChildren, ...slotted }: { default: string; [slotName: string]: string }
) => {
// Get the LitElement element instance.
let component = element.children[0];
// Check if hydration model is client:only
const isClientOnly = element.getAttribute('client') === 'only';
// We need to attach the element and it's children to the DOM since it's not
// SSR'd.
if (isClientOnly) {
component = new Component();
const otherSlottedChildren = Object.entries(slotted)
.map(([slotName, htmlStr]) => addSlotAttrsToHtmlString(slotName, htmlStr))
.join('');
// defaultChildren can actually be undefined, but TS will complain if we
// type it as so, make sure we don't render undefined.
component.innerHTML = `${defaultChildren ?? ''}${otherSlottedChildren}`;
element.appendChild(component);
// Set props bound to non-reactive properties as attributes.
for (let [name, value] of Object.entries(props)) {
if (!(name in Component.prototype)) {
component.setAttribute(name, value);
}
}
}
// If there is no deferral of hydration, then all reactive properties are
// already serialzied as reflected attributes, or no reactive props were set
// Alternatively, if hydration is client:only proceed to set props.
if (!component || !(component.hasAttribute('defer-hydration') || isClientOnly)) {
return;
}
// Set properties on the LitElement instance for resuming hydration.
for (let [name, value] of Object.entries(props)) {
// Check if reactive property or class property.
if (name in Component.prototype) {
(component as any)[name] = value;
}
}
// Tell LitElement to resume hydration.
component.removeAttribute('defer-hydration');
};