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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* Define getters and setters for observedAttributes converted to camelCase and
* trigger a batched aynchronous call to `render` upon observed
* attribute/property changes.
*/
export default function ObservedPropertiesMixin(superClass) {
return class ObservedProperties extends superClass {
static kebabToCamelCase(name) {
return name.replace(/-([a-z])/g, ($0, $1) => $1.toUpperCase());
}
constructor() {
super();
this._observedPropertiesMixin = {
pendingRender: false,
};
// Reflect property changes for `observedAttributes` to attributes.
for (let name of this.constructor.observedAttributes || []) {
if (name in this) {
// Don't overwrite existing properties.
continue;
}
// Convert attribute names from kebab-case to camelCase properties
Object.defineProperty(this, ObservedProperties.kebabToCamelCase(name), {
configurable: true,
get() {
return this.getAttribute(name);
},
set(value) {
if (value === null || value === undefined || value === false) {
this.removeAttribute(name);
} else {
this.setAttribute(name, value);
}
},
});
}
}
async _invalidateFromObservedPropertiesMixin() {
if (this._observedPropertiesMixin.pendingRender) {
return;
}
this._observedPropertiesMixin.pendingRender = true;
await Promise.resolve();
try {
this.render();
} finally {
this._observedPropertiesMixin.pendingRender = false;
}
}
attributeChangedCallback(attr, oldValue, newValue) {
if (super.attributeChangedCallback) {
super.attributeChangedCallback(attr, oldValue, newValue);
}
if (oldValue === newValue) {
return;
}
this._invalidateFromObservedPropertiesMixin();
}
};
}
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