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January 29, 2023 07:47
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HTML Expandable UL - Custom element
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| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="UTF-8"> | |
| <meta http-equiv="X-UA-Compatible" content="IE=edge"> | |
| <meta name="viewport" content="width=device-width, initial-scale=1.0"> | |
| <title>HTML Custom Element - Expandable List</title> | |
| </head> | |
| <body> | |
| <ul is="expandable-list"> | |
| <li>First</li> | |
| <li>Second</li> | |
| <ul is="expandable-list" data-expanded="false"> | |
| <li>First</li> | |
| <li>Second</li> | |
| </ul> | |
| </ul> | |
| <script> | |
| class ExpandableList extends HTMLUListElement { | |
| constructor() { | |
| super() | |
| this.style.position = 'relative' | |
| this.toggleBtn = document.createElement('button') | |
| this.toggleBtn.style.position = 'absolute' | |
| this.toggleBtn.style.border = 'none' | |
| this.toggleBtn.style.background = 'none' | |
| this.toggleBtn.style.padding = 0 | |
| this.toggleBtn.style.top = 0 | |
| this.toggleBtn.style.left = '5px' | |
| this.toggleBtn.style.cursor = 'pointer' | |
| this.toggleBtn.innerText = '>' | |
| this.toggleBtn.addEventListener('click', () => { | |
| this.dataset.expanded = !this.isExpanded | |
| }) | |
| this.appendChild(this.toggleBtn) | |
| } | |
| get isExpanded() { | |
| return ( | |
| this.dataset.expanded !== 'false' && | |
| this.dataset.expanded != null | |
| ) | |
| } | |
| static get observedAttributes() { | |
| return ['data-expanded'] | |
| } | |
| attributeChangedCallback(name, oldValue, newValue) { | |
| this.updateStyles() | |
| } | |
| connectedCallback() { | |
| if (this.dataset.expanded == null) { | |
| this.dataset.expanded = true | |
| } | |
| this.updateStyles() | |
| } | |
| updateStyles() { | |
| const transform = this.isExpanded ? 'rotate(90deg)' : '' | |
| this.toggleBtn.style.transform = transform | |
| ;[...this.children].forEach(child => { | |
| child.style.display = this.isExpanded ? '' : 'none' | |
| }) | |
| this.toggleBtn.style.display = '' | |
| } | |
| } | |
| customElements.define( | |
| 'expandable-list', | |
| ExpandableList, | |
| { extends: 'ul' } | |
| ) | |
| </script> | |
| </body> | |
| </html> |
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