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March 4, 2021 08:19
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Vanilla Lazy Load
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//source: https://www.merixstudio.com/blog/lazy-loading-pure-javascript/ | |
function lazyLoadInit(){ | |
let lazyImages = [].slice.call(document.querySelectorAll("img.lazy")); | |
let active = false; | |
var treshold = 100; | |
const lazyLoad = function() { | |
if (active === false) { | |
active = true; | |
setTimeout(function() { | |
lazyImages.forEach(function(lazyImage) { | |
if ((lazyImage.getBoundingClientRect().top-treshold <= window.innerHeight && lazyImage.getBoundingClientRect().bottom+treshold >= 0)) { | |
lazyImage.src = lazyImage.dataset.src; | |
lazyImage.classList.remove("lazy"); | |
lazyImages = lazyImages.filter(function(image) { | |
return image !== lazyImage; | |
}); | |
if (lazyImages.length === 0) { | |
document.removeEventListener("scroll", lazyLoad); | |
window.removeEventListener("orientationchange", lazyLoad); | |
} | |
} | |
}); | |
active = false; | |
}, 200); | |
} | |
}; | |
document.addEventListener("scroll", lazyLoad); | |
window.addEventListener("resize", lazyLoad); | |
window.addEventListener("orientationchange", lazyLoad); | |
document.dispatchEvent(new CustomEvent('scroll')) | |
} | |
AddOnLoadEvent(lazyLoadInit); | |
/* | |
//ADD TO ON LOAD EVENT | |
function AddOnLoadEvent(functionX) { | |
var oldonloadevent = window.onload; | |
if (typeof window.onload != 'function') { | |
window.onload = functionX; | |
} | |
else { | |
window.onload = function () { | |
if (oldonloadevent) { | |
oldonloadevent(); | |
} | |
functionX(); | |
} | |
} | |
} | |
*/ |
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