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IntersectionObserver test (padding)
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| <!doctype html> | |
| <html lang="en"> | |
| <head> | |
| <title>IntersectionObserver test (padding)</title> | |
| <style> | |
| body { | |
| margin: 0 auto; | |
| padding: 10px; | |
| max-width: 800px; | |
| } | |
| .flex { | |
| display: flex; | |
| } | |
| .container { | |
| width: 200px; | |
| height: 600px; | |
| overflow-y: scroll; | |
| padding: 50px; | |
| } | |
| .box { | |
| height: 300px; | |
| display: flex; | |
| justify-content: center; | |
| align-items: center; | |
| border: none; | |
| margin: 0; | |
| padding: 0; | |
| } | |
| .box:nth-child(even) { | |
| background: #aaa; | |
| } | |
| .box:nth-child(odd) { | |
| background: #ccc; | |
| } | |
| .display { | |
| width: 200px; | |
| height: 100%; | |
| margin-left: 50px; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <h1>IntersectionObserver test (padding)</h1> | |
| <div class="flex"> | |
| <div class="container"> | |
| <div id="box0" class="box"> | |
| Hello | |
| </div> | |
| <div id="box1" class="box"> | |
| world | |
| </div> | |
| <div id="box2" class="box"> | |
| Intersection | |
| </div> | |
| <div id="box3" class="box"> | |
| Observer | |
| </div> | |
| </div> | |
| <pre class="display">Output: | |
| </pre> | |
| </div> | |
| <script> | |
| document.addEventListener('DOMContentLoaded', () => { | |
| const $ = document.querySelector.bind(document) | |
| const $$ = _ => Array.from(document.querySelectorAll(_)) | |
| const display = $('.display') | |
| function log(str) { | |
| display.textContent += (str || '') + '\n' | |
| } | |
| function onObserve(entries) { | |
| entries.forEach(entry => { | |
| const { | |
| isIntersecting, | |
| intersectionRatio | |
| } = entry | |
| const thresholds = observer.thresholds | |
| const id = entry.target.id | |
| log(`onObserve event! thresholds: ${JSON.stringify(thresholds)}, id: ${id}, isIntersecting: ${isIntersecting}, intersectionRatio: ${intersectionRatio}`) | |
| }) | |
| } | |
| const observer = new IntersectionObserver(onObserve, { | |
| root: $('.container'), | |
| rootMargin: '0px 100%', | |
| threshold: 0 | |
| }) | |
| observer.observe($('#box3')) | |
| function jsonifyGBCR(el) { | |
| var rect = el.getBoundingClientRect() | |
| return { | |
| left: rect.left, | |
| top: rect.top, | |
| height: rect.height, | |
| width: rect.width | |
| } | |
| } | |
| log('container\'s gBCR: ' + JSON.stringify(jsonifyGBCR($('.container')))) | |
| setTimeout(() => { | |
| log('scrolled down') | |
| $('.container').scrollTop = 250 | |
| setTimeout(() => { | |
| log('scrolled to top') | |
| $('.container').scrollTop = 0 | |
| }, 400) | |
| }, 400) | |
| }) | |
| </script> | |
| </body> | |
| </html> |
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