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Dreaming of HTML imports 🤔
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| // Example usage: | |
| // <script type="module" src="./html-import.js"></script> | |
| // <html-import href="./example.html" runscripts></html-import> | |
| // <!-- now we can use the component defined from example.html --> | |
| // <example-custom-element><p>This paragraph will be slotted.</p></example-custom-element> | |
| export class HTMLImport extends HTMLElement { | |
| static { | |
| customElements.define('html-import', this) | |
| } | |
| static get observedAttributes() { | |
| return ['href'] | |
| } | |
| constructor() { | |
| super() | |
| this.attachShadow({ mode: 'open' }) | |
| } | |
| attributeChangedCallback(name, _oldValue, newValue) { | |
| if (name !== 'href') { return } | |
| this.#doFetch(newValue) | |
| } | |
| #clear() { | |
| while(this.firstChild) this.removeChild(this.lastChild) | |
| while(this.shadowRootfirstChild) this.removeChild(this.shadowRoot.lastChild) | |
| } | |
| async #doFetch(href) { | |
| if (!href) { | |
| this.#clear() | |
| return | |
| } | |
| const parser = new DOMParser() | |
| const response = await fetch(href) | |
| const text = await response.text() | |
| const doc = parser.parseFromString(text, 'text/html') | |
| const template = document.createElement('template') | |
| template.innerHTML = doc.body.innerHTML | |
| const hrefNow = this.getAttribute('href') | |
| if (hrefNow === href) { | |
| this.#clear() | |
| this.shadowRoot.append(template) | |
| this.append(template.content.cloneNode(true)) | |
| const runScripts = this.getAttribute('runscripts') !== null | |
| if (runScripts) { | |
| for (const el of doc.body.children) { | |
| if (el.tagName === 'SCRIPT') { | |
| const script = document.createElement('script') | |
| script.innerHTML = el.textContent | |
| if (el.src) { script.src = el.src } | |
| if (el.type) { script.type = el.type } | |
| this.append(script) | |
| } | |
| } | |
| } | |
| } | |
| } | |
| } |
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| <!doctype html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8" /> | |
| <title>This is an HTML page!</title> | |
| </head> | |
| <body> | |
| <template data-name="example-custom-element"> | |
| <style> | |
| p, ::slotted(p) { | |
| font-style: italic; | |
| } | |
| </style> | |
| <p>This is a paragraph from the template in example.html</p> | |
| <slot></slot> | |
| </template> | |
| <script> | |
| customElements.define('example-custom-element', class extends HTMLElement { | |
| constructor() { | |
| super() | |
| this.attachShadow({ mode: 'open' }) | |
| } | |
| connectedCallback() { | |
| const template = document.querySelector('template[data-name="example-custom-element"]') | |
| this.shadowRoot.append(template.content.cloneNode(true)) | |
| const p = document.createElement('p') | |
| p.innerText = 'This is a paragraph from the connectedCallback() in example.html to prove that scripts run' | |
| this.shadowRoot.append(p) | |
| } | |
| }) | |
| </script> | |
| </body> | |
| </html> |
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