Created
July 29, 2020 01:43
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IntersectionObserver memo
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| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="UTF-8"> | |
| <title>Intersection Observer</title> | |
| <style> | |
| #outer { | |
| height: 500px; | |
| width: calc(100vw - 100px); | |
| margin-top: calc((100vh - 500px)/2); | |
| margin-left: auto; | |
| margin-right: auto; | |
| overflow-y: scroll; | |
| border: 1px solid #000; | |
| } | |
| #inner-top { | |
| background-color: #392734; | |
| color: #aefddf; | |
| } | |
| #inner-bottom { | |
| height: 100px; | |
| background-color: #defa33; | |
| color: #223932; | |
| line-height: 20px; | |
| padding-top: calc((100px - 20px)/2); | |
| text-align: center; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <section id="outer"> | |
| <section id="inner-top"> | |
| a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a a<br/>a | |
| </section> | |
| <section id="inner-bottom"> | |
| When this is shown, observer reacts something! | |
| </section> | |
| </section> | |
| <script> | |
| document.addEventListener('DOMContentLoaded', () => { | |
| const elemRoot = document.getElementById('outer'); | |
| const elemTarget = document.getElementById('inner-bottom'); | |
| const options = { | |
| root: elemRoot, | |
| rootMargin: '0px', | |
| threshold: 1.0, | |
| }; | |
| const callback = (entries, observer) => { | |
| const entry = entries[0]; | |
| if (entry.isIntersection) { | |
| console.log('shown', entry); | |
| } | |
| } | |
| const observer = new IntersectionObserver(callback, options); | |
| observer.observe(elemTarget); | |
| }); | |
| </script> | |
| </body> | |
| </html> |
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