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lazy load image set
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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>Document</title> | |
| <style> | |
| .bg-lz-load { | |
| background: white; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <div class="bg-lz-load" data-lz="image-set(url('image-1') 1x, url('image-2') 2x)"> | |
| </div> | |
| <script> | |
| const OnScreenObserver = new IntersectionObserver( | |
| (entries) => { | |
| entries.forEach((entry) => { | |
| const element = entry.target; | |
| const visiblePct = Math.floor(entry.intersectionRatio * 100); | |
| if (visiblePct > 10) { | |
| // lazyload execution | |
| element.classList.add('lz-loaded'); | |
| element.style.setProperty("background", element.dataset.lz); | |
| OnScreenObserver.unobserve(element); | |
| } | |
| }); | |
| }, | |
| { root: null, rootMargin: "0px", threshold: [0.2] }, | |
| ); | |
| [...document.querySelectorAll(".bg-lz-load:not.lz-loaded")].forEach(el => OnScreenObserver.observe(el)); | |
| </script> | |
| </body> | |
| </html> |
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