Created
April 7, 2022 16:46
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Simple snippet for creating vanilla web components.
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| export const define = ( | |
| name: string, | |
| ElCtor: CustomElementConstructor, | |
| options?: ElementDefinitionOptions | |
| ): void => { | |
| if (typeof window !== 'undefined') { | |
| customElements.define(name, ElCtor, options) | |
| } | |
| } | |
| if (typeof window === 'undefined') { | |
| global.HTMLElement = function () { | |
| // | |
| } as any | |
| } | |
| export abstract class CustomElement extends HTMLElement { | |
| public mountPoint: HTMLElement | null = null | |
| public shadowRoot: ShadowRoot | null = null | |
| protected shouldUpdate(_previous: any, _next: any): boolean { | |
| return true | |
| } | |
| protected createMountPoint(): void { | |
| this.mountPoint = document.createElement('div') | |
| this.mountPoint.innerHTML = this.render() | |
| this.shadowRoot = this.attachShadow({ mode: 'open' }) | |
| this.shadowRoot.appendChild(this.mountPoint) | |
| } | |
| protected destroyMountPoint(): void { | |
| if (this.mountPoint) { | |
| this.shadowRoot?.removeChild(this.mountPoint) | |
| } | |
| this.mountPoint = null | |
| this.shadowRoot = null | |
| } | |
| protected async connect(): Promise<void> { | |
| return | |
| } | |
| protected async connectedCallback(): Promise<void> { | |
| await this.connect() | |
| this.createMountPoint() | |
| } | |
| protected disconnect(): void { | |
| return | |
| } | |
| protected disconnectedCallback(): void { | |
| this.disconnect() | |
| this.destroyMountPoint() | |
| } | |
| protected forceRender(): void { | |
| this.mountPoint.innerHTML = this.render() | |
| } | |
| protected maybeRender(oldValue: any, newValue: any): void { | |
| if (this.mountPoint && this.shouldUpdate(oldValue, newValue)) { | |
| this.forceRender() | |
| } | |
| } | |
| protected attributeChangedCallback(_name: string, oldValue: any, newValue: any): void { | |
| this.maybeRender(oldValue, newValue) | |
| } | |
| abstract render(): string | |
| } |
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