Created
March 6, 2022 16:54
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| <!DOCTYPE html> | |
| <body></body> | |
| <script> | |
| class Element extends HTMLElement { | |
| #globalEventListeners = []; | |
| constructor(is, styles, properties, reflectedProperties) { | |
| super(); | |
| const style = document.createElement("style"); | |
| style.textContent = styles; | |
| const element = document.createElement(is); | |
| for (const [key, value] of Object.entries(properties)) { | |
| if (key in element) { | |
| element[key] = value; | |
| } else if (typeof value === "function") { | |
| addEventListener(key, value); | |
| this.#globalEventListeners.push([key, value]); | |
| } | |
| } | |
| for (const property of reflectedProperties) { | |
| Object.defineProperty(this, property, { | |
| get: () => element[property], | |
| set: (value) => element[property] = value | |
| }); | |
| } | |
| this.attachShadow({ mode: "open" }).replaceChildren(style, element); | |
| } | |
| disconnectedCallback() { | |
| for (const [key, value] of this.#globalEventListeners) { | |
| removeEventListener(key, value); | |
| } | |
| } | |
| } | |
| function defineCustomElement(tagName, { is, reflectedProperties, styles }) { | |
| const definition = class extends Element { | |
| constructor(properties) { | |
| super(is, styles, properties, reflectedProperties); | |
| } | |
| } | |
| customElements.define(tagName, definition); | |
| return definition; | |
| } | |
| const xInput = defineCustomElement("x-input", { | |
| is: "input", | |
| reflectedProperties: ["value"], | |
| styles: /*css*/` | |
| input { | |
| border: 1px solid magenta; | |
| } | |
| .large { | |
| font-size: 2em; | |
| } | |
| ` | |
| }); | |
| function EntryNameInput() { | |
| const input = new xInput({ | |
| className: "large", | |
| maxLength: 128, | |
| oninput: () => { | |
| console.log(input.value); | |
| }, | |
| onentrynameupdate: ({ detail }) => { | |
| input.value = detail; | |
| } | |
| }); | |
| return input; | |
| } | |
| function sendEvent(name, detail) { | |
| dispatchEvent(new CustomEvent(`on${name}`, { detail })) | |
| } | |
| const form = document.createElement("form"); | |
| const input = new EntryNameInput(); | |
| form.appendChild(input); | |
| document.body.appendChild(form); | |
| </script> |
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