233 lines
7.0 KiB
JavaScript
233 lines
7.0 KiB
JavaScript
/*!
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hey, [be]Lazy.js - v1.3.1 - 2015.02.01
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A lazy loading and multi-serving image script
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(c) Bjoern Klinggaard - @bklinggaard - http://dinbror.dk/blazy
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*/
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;(function(root, blazy) {
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if (typeof define === 'function' && define.amd) {
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// AMD. Register bLazy as an anonymous module
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define(blazy);
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} else if (typeof exports === 'object') {
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// Node. Does not work with strict CommonJS, but
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// only CommonJS-like environments that support module.exports,
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// like Node.
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module.exports = blazy();
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} else {
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// Browser globals. Register bLazy on window
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root.Blazy = blazy();
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}
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})(this, function () {
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'use strict';
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//vars
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var source, options, viewport, images, count, isRetina, destroyed;
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//throttle vars
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var validateT, saveViewportOffsetT;
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// constructor
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function Blazy(settings) {
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//IE7- fallback for missing querySelectorAll support
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if (!document.querySelectorAll) {
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var s=document.createStyleSheet();
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document.querySelectorAll = function(r, c, i, j, a) {
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a=document.all, c=[], r = r.replace(/\[for\b/gi, '[htmlFor').split(',');
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for (i=r.length; i--;) {
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s.addRule(r[i], 'k:v');
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for (j=a.length; j--;) a[j].currentStyle.k && c.push(a[j]);
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s.removeRule(0);
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}
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return c;
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};
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}
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//init vars
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destroyed = true;
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images = [];
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viewport = {};
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//options
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options = settings || {};
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options.error = options.error || false;
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options.offset = options.offset || 100;
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options.success = options.success || false;
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options.selector = options.selector || '.b-lazy';
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options.separator = options.separator || '|';
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options.container = options.container ? document.querySelectorAll(options.container) : false;
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options.errorClass = options.errorClass || 'b-error';
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options.breakpoints = options.breakpoints || false;
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options.successClass = options.successClass || 'b-loaded';
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options.src = source = options.src || 'data-src';
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isRetina = window.devicePixelRatio > 1;
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viewport.top = 0 - options.offset;
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viewport.left = 0 - options.offset;
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//throttle, ensures that we don't call the functions too often
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validateT = throttle(validate, 25);
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saveViewportOffsetT = throttle(saveViewportOffset, 50);
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saveViewportOffset();
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//handle multi-served image src
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each(options.breakpoints, function(object){
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if(object.width >= window.screen.width) {
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source = object.src;
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return false;
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}
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});
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// start lazy load
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initialize();
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}
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/* public functions
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************************************/
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Blazy.prototype.revalidate = function() {
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initialize();
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};
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Blazy.prototype.load = function(element, force){
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if(!isElementLoaded(element)) loadImage(element, force);
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};
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Blazy.prototype.destroy = function(){
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if(options.container){
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each(options.container, function(object){
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unbindEvent(object, 'scroll', validateT);
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});
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}
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unbindEvent(window, 'scroll', validateT);
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unbindEvent(window, 'resize', validateT);
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unbindEvent(window, 'resize', saveViewportOffsetT);
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count = 0;
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images.length = 0;
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destroyed = true;
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};
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/* private helper functions
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************************************/
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function initialize(){
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// First we create an array of images to lazy load
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createImageArray(options.selector);
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// Then we bind resize and scroll events if not already binded
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if(destroyed) {
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destroyed = false;
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if(options.container) {
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each(options.container, function(object){
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bindEvent(object, 'scroll', validateT);
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});
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}
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bindEvent(window, 'resize', saveViewportOffsetT);
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bindEvent(window, 'resize', validateT);
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bindEvent(window, 'scroll', validateT);
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}
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// And finally, we start to lazy load. Should bLazy ensure domready?
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validate();
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}
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function validate() {
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for(var i = 0; i<count; i++){
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var image = images[i];
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if(elementInView(image) || isElementLoaded(image)) {
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Blazy.prototype.load(image);
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images.splice(i, 1);
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count--;
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i--;
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}
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}
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if(count === 0) {
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Blazy.prototype.destroy();
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}
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}
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function loadImage(ele, force){
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// if element is visible
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if(force || (ele.offsetWidth > 0 && ele.offsetHeight > 0)) {
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var dataSrc = ele.getAttribute(source) || ele.getAttribute(options.src); // fallback to default data-src
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if(dataSrc) {
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var dataSrcSplitted = dataSrc.split(options.separator);
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var src = dataSrcSplitted[isRetina && dataSrcSplitted.length > 1 ? 1 : 0];
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var img = new Image();
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// cleanup markup, remove data source attributes
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each(options.breakpoints, function(object){
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ele.removeAttribute(object.src);
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});
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ele.removeAttribute(options.src);
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img.onerror = function() {
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if(options.error) options.error(ele, "invalid");
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ele.className = ele.className + ' ' + options.errorClass;
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};
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img.onload = function() {
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// Is element an image or should we add the src as a background image?
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ele.nodeName.toLowerCase() === 'img' ? ele.src = src : ele.style.backgroundImage = 'url("' + src + '")';
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ele.className = ele.className + ' ' + options.successClass;
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if(options.success) options.success(ele);
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};
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img.src = src; //preload image
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} else {
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if(options.error) options.error(ele, "missing");
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ele.className = ele.className + ' ' + options.errorClass;
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}
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}
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}
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function elementInView(ele) {
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var rect = ele.getBoundingClientRect();
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return (
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// Intersection
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rect.right >= viewport.left
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&& rect.bottom >= viewport.top
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&& rect.left <= viewport.right
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&& rect.top <= viewport.bottom
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);
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}
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function isElementLoaded(ele) {
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return (' ' + ele.className + ' ').indexOf(' ' + options.successClass + ' ') !== -1;
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}
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function createImageArray(selector) {
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var nodelist = document.querySelectorAll(selector);
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count = nodelist.length;
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//converting nodelist to array
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for(var i = count; i--; images.unshift(nodelist[i])){}
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}
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function saveViewportOffset(){
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viewport.bottom = (window.innerHeight || document.documentElement.clientHeight) + options.offset;
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viewport.right = (window.innerWidth || document.documentElement.clientWidth) + options.offset;
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}
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function bindEvent(ele, type, fn) {
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if (ele.attachEvent) {
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ele.attachEvent && ele.attachEvent('on' + type, fn);
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} else {
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ele.addEventListener(type, fn, false);
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}
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}
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function unbindEvent(ele, type, fn) {
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if (ele.detachEvent) {
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ele.detachEvent && ele.detachEvent('on' + type, fn);
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} else {
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ele.removeEventListener(type, fn, false);
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}
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}
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function each(object, fn){
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if(object && fn) {
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var l = object.length;
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for(var i = 0; i<l && fn(object[i], i) !== false; i++){}
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}
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}
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function throttle(fn, minDelay) {
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var lastCall = 0;
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return function() {
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var now = +new Date();
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if (now - lastCall < minDelay) {
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return;
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}
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lastCall = now;
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fn.apply(images, arguments);
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};
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}
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return Blazy;
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});
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