Created
March 23, 2012 14:55
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lazy loader
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta http-equiv="content-type" content="text/html; charset=UTF-8"> | |
| <title> - jsFiddle demo</title> | |
| <script type='text/javascript' src='lazyload.js'></script> | |
| <style type='text/css'> | |
| body { | |
| padding-top: 700px; | |
| } | |
| img { | |
| display: block; | |
| margin: 0 auto; | |
| } | |
| img.lazy { | |
| opacity: 0; | |
| transition: opacity 1s; | |
| -webkit-transition: opacity 1s; | |
| -moz-transition: opacity 1s; | |
| -o-transition: opacity 1s; | |
| } | |
| img.lazy.loaded { | |
| opacity: 1; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <img src="blank.gif" data-src="http://lorempixel.com/400/200/animals/1" width="400" height="200" class="lazy"> | |
| <br> | |
| <img src="blank.gif" data-src="http://lorempixel.com/400/200/animals/2" width="400" height="200" class="lazy"> | |
| <br> | |
| <img src="blank.gif" data-src="http://lorempixel.com/400/200/animals/3" width="400" height="200" class="lazy"> | |
| <br> | |
| <img src="blank.gif" data-src="http://lorempixel.com/400/200/animals/4" width="400" height="200" class="lazy"> | |
| </body> | |
| </html> |
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| img.lazy { | |
| opacity: 0; | |
| transition: opacity 1s; | |
| -webkit-transition: opacity 1s; | |
| -moz-transition: opacity 1s; | |
| -o-transition: opacity 1s; | |
| } | |
| img.lazy.loaded { | |
| opacity: 1; | |
| } |
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| /* lazyload.js (c) Lorenzo Giuliani | |
| * MIT License (http://www.opensource.org/licenses/mit-license.html) | |
| * | |
| * expects a list of: | |
| * `<img src="blank.gif" data-src="my_image.png" width="600" height="400" class="lazy">` | |
| */ | |
| !function(){ | |
| var $q = function(q, res){ | |
| if (document.querySelectorAll) { | |
| res = document.querySelectorAll(q); | |
| } else { | |
| var d=document | |
| , a=d.styleSheets[0] || d.createStyleSheet(); | |
| a.addRule(q,'f:b'); | |
| for(var l=d.all,b=0,c=[],f=l.length;b<f;b++) | |
| l[b].currentStyle.f && c.push(l[b]); | |
| a.removeRule(0); | |
| res = c; | |
| } | |
| return res; | |
| } | |
| , addEventListener = function(evt, fn){ | |
| window.addEventListener | |
| ? this.addEventListener(evt, fn, false) | |
| : (window.attachEvent) | |
| ? this.attachEvent('on' + evt, fn) | |
| : this['on' + evt] = fn; | |
| } | |
| , _has = function(obj, key) { | |
| return Object.prototype.hasOwnProperty.call(obj, key); | |
| } | |
| ; | |
| function loadImage (el, fn) { | |
| var img = new Image() | |
| , src = el.getAttribute('data-src'); | |
| img.onload = function() { | |
| el.src = src; | |
| el.className = el.getAttribute('class') + " loaded"; | |
| fn? fn() : null; | |
| } | |
| img.src = src; | |
| } | |
| function elementInViewport(el) { | |
| var rect = el.getBoundingClientRect() | |
| return ( | |
| rect.top >= 0 | |
| && rect.left >= 0 | |
| && rect.top <= (window.innerHeight || document.documentElement.clientHeight) | |
| ) | |
| } | |
| addEventListener('load', function(){ | |
| var images = new Array() | |
| , query = $q('img.lazy') | |
| , processScroll = function(){ | |
| for (var i = 0; i < images.length; i++) { | |
| if (elementInViewport(images[i])) { | |
| loadImage(images[i], function () { | |
| images.splice(i, i); | |
| }); | |
| } | |
| }; | |
| } | |
| ; | |
| // Array.prototype.slice.call is not callable under our lovely IE8 | |
| for (var i = 0; i < query.length; i++) { | |
| images.push(query[i]); | |
| }; | |
| processScroll(); | |
| addEventListener('scroll',processScroll); | |
| }); | |
| }(); |
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