!function(t,i){"function"==typeof define&&define.amd?define([],i):"object"==typeof exports?module.exports=i():t.Layzr=i()}(this,function(){"use strict";function t(t){this._lastScroll=0,this._ticking=!1,t=t||{},this._optionsContainer=document.querySelector(t.container)||window,this._optionsSelector=t.selector||"[data-layzr]",this._optionsAttr=t.attr||"data-layzr",this._optionsAttrRetina=t.retinaAttr||"data-layzr-retina",this._optionsAttrBg=t.bgAttr||"data-layzr-bg",this._optionsAttrHidden=t.hiddenAttr||"data-layzr-hidden",this._optionsThreshold=t.threshold||0,this._optionsCallback=t.callback||null,this._retina=window.devicePixelRatio>1,this._srcAttr=this._retina?this._optionsAttrRetina:this._optionsAttr,this._nodes=document.querySelectorAll(this._optionsSelector),this._handlerBind=this._requestScroll.bind(this),this._create()}return t.prototype._requestScroll=function(){this._lastScroll=this._optionsContainer===window?window.pageYOffset:this._optionsContainer.scrollTop+this._getOffset(this._optionsContainer),this._requestTick()},t.prototype._requestTick=function(){this._ticking||(requestAnimationFrame(this.update.bind(this)),this._ticking=!0)},t.prototype._getOffset=function(t){return t.getBoundingClientRect().top+window.pageYOffset},t.prototype._getContainerHeight=function(){return this._optionsContainer.innerHeight||this._optionsContainer.offsetHeight},t.prototype._create=function(){this._handlerBind(),this._optionsContainer.addEventListener("scroll",this._handlerBind,!1),this._optionsContainer.addEventListener("resize",this._handlerBind,!1)},t.prototype._destroy=function(){this._optionsContainer.removeEventListener("scroll",this._handlerBind,!1),this._optionsContainer.removeEventListener("resize",this._handlerBind,!1)},t.prototype._inViewport=function(t){var i=this._lastScroll,e=i+this._getContainerHeight(),o=this._getOffset(t),n=o+this._getContainerHeight(),s=this._optionsThreshold/100*window.innerHeight;return n>=i-s&&e+s>=o&&!t.hasAttribute(this._optionsAttrHidden)},t.prototype._reveal=function(t){var i=t.getAttribute(this._srcAttr)||t.getAttribute(this._optionsAttr);t.hasAttribute(this._optionsAttrBg)?t.style.backgroundImage="url("+i+")":t.setAttribute("src",i),"function"==typeof this._optionsCallback&&this._optionsCallback.call(t),t.removeAttribute(this._optionsAttr),t.removeAttribute(this._optionsAttrRetina),t.removeAttribute(this._optionsAttrBg),t.removeAttribute(this._optionsAttrHidden)},t.prototype.updateSelector=function(){this._nodes=document.querySelectorAll(this._optionsSelector)},t.prototype.update=function(){for(var t=this._nodes.length,i=0;t>i;i++){var e=this._nodes[i];e.hasAttribute(this._optionsAttr)&&this._inViewport(e)&&this._reveal(e)}this._ticking=!1},t});