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[Отложенная загрузка изображений] Загрузка изображений с помощью Intersection Observer API #lazy #js
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* { | |
font-family: sans-serif; | |
} | |
#container { | |
font-size: 20px; | |
line-height: 30px; | |
max-width: 600px; | |
} | |
#bg-image.lazy { | |
background-image: none; | |
background-color: #F1F1FA; | |
} | |
#bg-image { | |
background-image: url("https://ik.imagekit.io/demo/img/image10.jpeg?tr=w-600,h-400"); | |
max-width: 600px; | |
height: 400px; | |
} |
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<img src="https://ik.imagekit.io/demo/img/image1.jpeg?tr=w-400,h-300" /> | |
<img src="https://ik.imagekit.io/demo/img/image2.jpeg?tr=w-400,h-300" /> | |
<img src="https://ik.imagekit.io/demo/img/image3.jpg?tr=w-400,h-300" /> | |
<img class="lazy" data-src="https://ik.imagekit.io/demo/img/image4.jpeg?tr=w-400,h-300" /> | |
<img class="lazy" data-src="https://ik.imagekit.io/demo/img/image5.jpeg?tr=w-400,h-300" /> | |
<img class="lazy" data-src="https://ik.imagekit.io/demo/img/image6.jpeg?tr=w-400,h-300" /> | |
<img class="lazy" data-src="https://ik.imagekit.io/demo/img/image7.jpeg?tr=w-400,h-300" /> | |
<div id="bg-image" class="lazy"></div> | |
<img class="lazy" data-src="https://ik.imagekit.io/demo/img/image8.jpeg?tr=w-400,h-300" /> | |
<img class="lazy" data-src="https://ik.imagekit.io/demo/img/image9.jpeg?tr=w-400,h-300" /> | |
<img class="lazy" data-src="https://ik.imagekit.io/demo/img/image10.jpeg?tr=w-400,h-300" /> |
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document.addEventListener("DOMContentLoaded", function() { | |
var lazyloadImages; | |
if ("IntersectionObserver" in window) { | |
lazyloadImages = document.querySelectorAll(".lazy"); | |
var imageObserver = new IntersectionObserver(function(entries, observer) { | |
entries.forEach(function(entry) { | |
if (entry.isIntersecting) { | |
var image = entry.target; | |
image.src = image.dataset.src; | |
image.classList.remove("lazy"); | |
imageObserver.unobserve(image); | |
} | |
}); | |
}); | |
lazyloadImages.forEach(function(image) { | |
imageObserver.observe(image); | |
}); | |
} else { | |
var lazyloadThrottleTimeout; | |
lazyloadImages = document.querySelectorAll(".lazy"); | |
function lazyload () { | |
if(lazyloadThrottleTimeout) { | |
clearTimeout(lazyloadThrottleTimeout); | |
} | |
lazyloadThrottleTimeout = setTimeout(function() { | |
var scrollTop = window.pageYOffset; | |
lazyloadImages.forEach(function(img) { | |
if(img.offsetTop < (window.innerHeight + scrollTop)) { | |
img.src = img.dataset.src; | |
img.classList.remove('lazy'); | |
} | |
}); | |
if(lazyloadImages.length == 0) { | |
document.removeEventListener("scroll", lazyload); | |
window.removeEventListener("resize", lazyload); | |
window.removeEventListener("orientationChange", lazyload); | |
} | |
}, 20); | |
} | |
document.addEventListener("scroll", lazyload); | |
window.addEventListener("resize", lazyload); | |
window.addEventListener("orientationChange", lazyload); | |
} | |
}) | |
// Это тот же самый скрипт но подгружает лениво изображения прописанный в css | |
document.addEventListener("DOMContentLoaded", function() { | |
var lazyloadImages; | |
if ("IntersectionObserver" in window) { | |
lazyloadImages = document.querySelectorAll(".lazy"); | |
var imageObserver = new IntersectionObserver(function(entries, observer) { | |
entries.forEach(function(entry) { | |
if (entry.isIntersecting) { | |
var image = entry.target; | |
image.classList.remove("lazy"); | |
imageObserver.unobserve(image); | |
} | |
}); | |
}); | |
lazyloadImages.forEach(function(image) { | |
imageObserver.observe(image); | |
}); | |
} else { | |
var lazyloadThrottleTimeout; | |
lazyloadImages = document.querySelectorAll(".lazy"); | |
function lazyload () { | |
if(lazyloadThrottleTimeout) { | |
clearTimeout(lazyloadThrottleTimeout); | |
} | |
lazyloadThrottleTimeout = setTimeout(function() { | |
var scrollTop = window.pageYOffset; | |
lazyloadImages.forEach(function(img) { | |
if(img.offsetTop < (window.innerHeight + scrollTop)) { | |
img.src = img.dataset.src; | |
img.classList.remove('lazy'); | |
} | |
}); | |
if(lazyloadImages.length == 0) { | |
document.removeEventListener("scroll", lazyload); | |
window.removeEventListener("resize", lazyload); | |
window.removeEventListener("orientationChange", lazyload); | |
} | |
}, 20); | |
} | |
document.addEventListener("scroll", lazyload); | |
window.addEventListener("resize", lazyload); | |
window.addEventListener("orientationChange", lazyload); | |
} | |
}) | |
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