48 lines
1.4 KiB
JavaScript
48 lines
1.4 KiB
JavaScript
export class BetterHTMLElement extends HTMLElement {
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attributeChangedCallback(name, old, value) { this[name+"Changed"](value, old) }
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// Array of connected callbacks
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#connected = [];
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// connectedCallback but as a promise.
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// Resolves instantly when already connected and can be used more than once.
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get connected() {
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if (this.isConnected) return Promise.resolve(this)
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else return new Promise( (yes, no) => this.#connected.push({yes, no}) )
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}
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// Resolves all `connected promises
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connectedCallback() {
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this.#connected.forEach( e => e.yes(this) );
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this.#connected = [];
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}
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// Fancier way to register an element
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// TODO: Unregister old names first
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// TODO: Register name internally
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static set tagName(name) { customElements.define(name, this) }
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// Adds property/attribute mappings to the object.
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static addProps(fields = this.observedAttributes) {
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fields.forEach( attr => Object.defineProperty(this.prototype, attr, {
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get() { return this.getAttribute(attr) },
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set(val) { this.setAttribute(attr, val) }
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}))
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}
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}
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/* Example:
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class FooBar extends BetterHTMLElement {
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static get observedAttributes() { return [ "name" ] }
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constructor() {
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super();
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this.attachShadow({mode: "open"});
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this.shadowRoot.innerHTML = `<h1>Hello, <span id="name"></span></h1>`
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}
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nameChanged(name) { this.shadowRoot.querySelector("#name").innerHTML=name; }
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}
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FooBar.addProps()
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FooBar.tagName = "foo-bar"
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*/
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