64 lines
1.8 KiB
JavaScript
64 lines
1.8 KiB
JavaScript
export class BetterHTMLElement extends HTMLElement {
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attributeChangedCallback(name, old, value) { if (name+"Changed" in this) 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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setContent(...content) {
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this.innerHTML = ""
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content.forEach( element => this.appendChild(element) )
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}
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set content(content) {
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this.setContent(content)
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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 initialize(name = this.name) {
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const names = Object
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.getOwnPropertyNames(this.prototype)
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.filter(name => name.search(/Changed$/)+1)
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.map(name => name.replace(/Changed$/, ''))
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Object.defineProperty(this, "observedAttributes", {
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get() { return names }
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})
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names.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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name = name.replace(/([a-z])([A-Z])/g, "$1-$2").toLowerCase()
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customElements.define(name, this)
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return name
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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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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.initialize()
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*/
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