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Sinple jQuery lazy-loading
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/** | |
* Shortcut to getBoundingClientRect | |
* @param {Element} element | |
*/ | |
function getRect(element) { | |
if (element === window) { | |
return { | |
top: 0, | |
right: element.innerWidth, | |
bottom: element.innerHeight, | |
left: 0, | |
height: element.innerHeight, | |
width: element.innerWidth | |
}; | |
} | |
var rect = element.getBoundingClientRect(); | |
return { | |
top: rect.top, | |
right: rect.right, | |
bottom: rect.bottom, | |
left: rect.left, | |
height: rect.height || (rect.bottom - rect.top), | |
width: rect.width || (rect.right - rect.left) | |
}; | |
} | |
/** | |
* Check if an element is even partially visible within a container | |
* @param {(Element|DOMRect)} container | |
* @param {(Element|DOMRect)} element | |
* @param {Number} threshold | |
* @return {Boolean} | |
*/ | |
function isInside(container, element, threshold) { | |
if (element && element.nodeType) { | |
element = getRect(element); | |
} | |
if (!element || (!element.top && !element.left && !element.bottom && !element.right)) { | |
// The element (or one of it's parents) is display: none | |
return false; | |
} | |
if (container && container.nodeType) { | |
container = getRect(container); | |
} | |
if (!container || (!container.top && !container.left && !container.bottom && !container.right)) { | |
// The container (or one of it's parents) is display: none | |
return false; | |
} | |
threshold = threshold || 0; | |
var containerTop = container.top - threshold, | |
containerBottom = container.bottom + threshold, | |
containerLeft = container.left - threshold, | |
containerRight = container.right + threshold; | |
return ((element.top >= containerTop && element.top <= containerBottom) | |
|| (element.bottom >= containerTop && element.bottom <= containerBottom) | |
|| (element.top < containerTop && element.bottom > containerBottom)) | |
&& ( | |
(element.left >= containerLeft && element.left <= containerRight) | |
|| (element.right >= containerLeft && element.right <= containerRight) | |
|| (element.left < containerLeft && element.right > containerRight)); | |
} | |
/** | |
* Lasy load images or anything else, search for data-<data-lazyload>, and when visible simply move that over to <data-lazyload> | |
*/ | |
$.fn.lazyLoad = function() { | |
var windowPos = getRect(window); | |
$(this).find("img[data-lazyload],source[data-lazyload]").each(function() { | |
if (isInside(this, windowPos, 200)) { | |
var $this = $(this), | |
attr = $this.attr("data-lazyload"); | |
$this | |
.attr(attr, $this.attr("data-" + attr)) | |
.removeAttr("data-lazyload") | |
.removeAttr("data-" + attr); | |
} | |
}); | |
}; |
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