IntersectionObserver api实现图片懒加载实例代码
IntersectionObserver实现图片懒加载相关教程,具体实例代码请看下文:
API:
https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API
直接上源码:
<!DOCTYPE html> <html> <header> <style> .list-item{ height: 400px; margin: 5px; background-color: lightblue; list-style: none; } </style> </header> <body> <li class = "list-item" ><img class = "list-item-img" data-src= './images/icon1.png' ></li> <li class = "list-item" ><img class = "list-item-img" data-src= './images/icon2.png' ></li> <li class = "list-item" ><img class = "list-item-img" data-src= './images/icon3.png' ></li> <li class = "list-item" ><img class = "list-item-img" data-src= './images/icon4.png' ></li> <li class = "list-item" ><img class = "list-item-img" data-src= './images/icon5.png' ></li> <li class = "list-item" ><img class = "list-item-img" data-src= './images/icon6.png' ></li> <script> var observer = new IntersectionObserver(function(changes) { console. log (changes); changes.forEach(function(element, index) { // statements if (element.intersectionRatio > 0 && element.intersectionRatio <= 1) { element.target.src = element.target.dataset.src; } }); }); function addObserver() { var listItems = document.querySelectorAll( '.list-item-img' ); listItems.forEach(function(item) { observer.observe(item); }); } addObserver(); </script> </body> </html> |
运行代码后发现,当滚动滚动轴时,只有当<li>区域完全显示出来后才会触发相应的下载图片的http请求。
兼容浏览器:
desktop:
THE END