(function(window,document){'use strict';var registry=[];if('IntersectionObserver'in window&&'IntersectionObserverEntry'in window&&'intersectionRatio'in window.IntersectionObserverEntry.prototype){if(!('isIntersecting'in window.IntersectionObserverEntry.prototype)){Object.defineProperty(window.IntersectionObserverEntry.prototype,'isIntersecting',{get:function(){return this.intersectionRatio>0;}});}
return;}
function now(){return window.performance&&performance.now&&performance.now();}
function getEmptyRect(){return{top:0,bottom:0,left:0,right:0,width:0,height:0};}
function getParentNode(node){var parent=node.parentNode;if(parent&&parseInt(parent.nodeType,10)===11&&parent.host){return parent.host;}
if(parent&&parent.assignedSlot){return parent.assignedSlot.parentNode;}
return parent;}
function containsDeep(parent,child){var node=child;while(node){if(node===parent){return true;}
node=getParentNode(node);}
return false;}
function addEvent(node,event,fn,opt_useCapture){if(typeof node.addEventListener==='function'){node.addEventListener(event,fn,opt_useCapture||false);}
else if(typeof node.attachEvent==='function'){node.attachEvent('on'+event,fn);}}
function throttle(fn,timeout){var timer=null;return function(){if(!timer){timer=setTimeout(function(){fn();timer=null;},timeout);}};}
function removeEvent(node,event,fn,opt_useCapture){if(typeof node.removeEventListener==='function'){node.removeEventListener(event,fn,opt_useCapture||false);}
else if(typeof node.detatchEvent==='function'){node.detatchEvent('on'+event,fn);}}
function getBoundingClientRect(el){var rect;try{rect=el.getBoundingClientRect();}catch(err){}
if(!rect){return getEmptyRect();}
if(!(rect.width&&rect.height)){rect={top:rect.top,right:rect.right,bottom:rect.bottom,left:rect.left,width:rect.right-rect.left,height:rect.bottom-rect.top};}
return rect;}
function computeRectIntersection(rect1,rect2){var top=Math.max(rect1.top,rect2.top),bottom=Math.min(rect1.bottom,rect2.bottom),left=Math.max(rect1.left,rect2.left),right=Math.min(rect1.right,rect2.right),width=right-left,height=bottom-top;return width>=0&&height>=0&&{top:top,bottom:bottom,left:left,right:right,width:width,height:height};}
function IntersectionObserverEntry(entry){var targetRect=entry.boundingClientRect,targetArea=targetRect.width*targetRect.height,intersectionRect=this.intersectionRect,intersectionArea=intersectionRect.width*intersectionRect.height;this.time=entry.time;this.target=entry.target;this.rootBounds=entry.rootBounds;this.boundingClientRect=targetRect;this.intersectionRect=entry.intersectionRect||getEmptyRect();this.isIntersecting=!!entry.intersectionRect;if(targetArea){this.intersectionRatio=Number((intersectionArea / targetArea).toFixed(4));}else{this.intersectionRatio=this.isIntersecting?1:0;}}
function IntersectionObserver(callback,opt_options){var options=opt_options||{};if(typeof callback!=='function'){throw new Error('callback must be a function');}
if(options.root&&parseInt(options.root.nodeType,10)!==1){throw new Error('root must be an Element');}
this._checkForIntersections=throttle(this._checkForIntersections.bind(this),this.THROTTLE_TIMEOUT);this._callback=callback;this._observationTargets=[];this._queuedEntries=[];this._rootMarginValues=this._parseRootMargin(options.rootMargin);this.thresholds=this._initThresholds(options.threshold);this.root=options.root||null;this.rootMargin=this._rootMarginValues.map(function(margin){return margin.value+margin.unit;}).join(' ');}
IntersectionObserver.prototype.THROTTLE_TIMEOUT=100;IntersectionObserver.prototype.POLL_INTERVAL=null;IntersectionObserver.prototype.USE_MUTATION_OBSERVER=true;IntersectionObserver.prototype.observe=function(target){var isTargetAlreadyObserved=this._observationTargets.some(function(item){return item.element==target;});if(isTargetAlreadyObserved){return;}
if(!(target&&parseInt(target.nodeType,10)===1)){throw new Error('target must be an Element');}
this._registerInstance();this._observationTargets.push({element:target,entry:null});this._monitorIntersections();this._checkForIntersections();};IntersectionObserver.prototype.unobserve=function(target){this._observationTargets=this._observationTargets.filter(function(item){return item.element!=target;});if(!this._observationTargets.length){this._unmonitorIntersections();this._unregisterInstance();}};IntersectionObserver.prototype.disconnect=function(){this._observationTargets=[];this._unmonitorIntersections();this._unregisterInstance();};IntersectionObserver.prototype.takeRecords=function(){var records=this._queuedEntries.slice();this._queuedEntries=[];return records;};IntersectionObserver.prototype._initThresholds=function(opt_threshold){var threshold=opt_threshold||[0];if(!Array.isArray(threshold)){threshold=[threshold];}
return threshold.sort().filter(function(t,i,a){if(typeof t!=='number'||isNaN(t)||t<0||t>1){throw new Error('threshold must be a number between 0 and 1 inclusively');}
return t!==a[i-1];});};IntersectionObserver.prototype._parseRootMargin=function(opt_rootMargin){var marginString=opt_rootMargin||'0px',margins=marginString.split(/\s+/).map(function(margin){var parts=/^(-?\d*\.?\d+)(px|%)$/.exec(margin);if(!parts){throw new Error('rootMargin must be specified in pixels or percent');}
return{value:parseFloat(parts[1]),unit:parts[2]};});margins[1]=margins[1]||margins[0];margins[2]=margins[2]||margins[0];margins[3]=margins[3]||margins[1];return margins;};IntersectionObserver.prototype._monitorIntersections=function(){if(this._monitoringIntersections){return;}
this._monitoringIntersections=true;if(this.POLL_INTERVAL){this._monitoringInterval=setInterval(this._checkForIntersections,this.POLL_INTERVAL);}
else{addEvent(window,'resize',this._checkForIntersections,true);addEvent(document,'scroll',this._checkForIntersections,true);if(this.USE_MUTATION_OBSERVER&&'MutationObserver'in window){this._domObserver=new MutationObserver(this._checkForIntersections);this._domObserver.observe(document,{attributes:true,childList:true,characterData:true,subtree:true});}}};IntersectionObserver.prototype._unmonitorIntersections=function(){if(this._monitoringIntersections){this._monitoringIntersections=false;clearInterval(this._monitoringInterval);this._monitoringInterval=null;removeEvent(window,'resize',this._checkForIntersections,true);removeEvent(document,'scroll',this._checkForIntersections,true);if(this._domObserver){this._domObserver.disconnect();this._domObserver=null;}}};IntersectionObserver.prototype._checkForIntersections=function(){var rootIsInDom=this._rootIsInDom(),rootRect=rootIsInDom?this._getRootRect():getEmptyRect();this._observationTargets.forEach(function(item){var target=item.element,targetRect=getBoundingClientRect(target),rootContainsTarget=this._rootContainsTarget(target),oldEntry=item.entry,intersectionRect=rootIsInDom&&rootContainsTarget&&this._computeTargetAndRootIntersection(target,rootRect),newEntry=item.entry=new IntersectionObserverEntry({time:now(),target:target,boundingClientRect:targetRect,rootBounds:rootRect,intersectionRect:intersectionRect});if(!oldEntry){this._queuedEntries.push(newEntry);}else if(rootIsInDom&&rootContainsTarget){if(this._hasCrossedThreshold(oldEntry,newEntry)){this._queuedEntries.push(newEntry);}}else if(oldEntry&&oldEntry.isIntersecting){this._queuedEntries.push(newEntry);}},this);if(this._queuedEntries.length){this._callback(this.takeRecords(),this);}};IntersectionObserver.prototype._computeTargetAndRootIntersection=function(target,rootRect){var targetRect,intersectionRect,parent,atRoot=false,parentRect=null,parentComputedStyle;if(window.getComputedStyle(target).display==='none'){return;}
targetRect=getBoundingClientRect(target);intersectionRect=targetRect;parent=getParentNode(target);while(!atRoot){parentComputedStyle=parseInt(parent.nodeType,10)===1?window.getComputedStyle(parent):{};if(parentComputedStyle.display==='none'){return;}
if(parent==this.root||parent==document){atRoot=true;parentRect=rootRect;}else if(parent!=document.body&&parent!=document.documentElement&&parentComputedStyle.overflow!=='visible'){parentRect=getBoundingClientRect(parent);}
if(parentRect){intersectionRect=computeRectIntersection(parentRect,intersectionRect);if(!intersectionRect){break;}}
parent=getParentNode(parent);}
return intersectionRect;};IntersectionObserver.prototype._getRootRect=function(){var rootRect,html,body;if(this.root){rootRect=getBoundingClientRect(this.root);}else{html=document.documentElement;body=document.body;rootRect={top:0,left:0,right:html.clientWidth||body.clientWidth,width:html.clientWidth||body.clientWidth,bottom:html.clientHeight||body.clientHeight,height:html.clientHeight||body.clientHeight};}
return this._expandRectByRootMargin(rootRect);};IntersectionObserver.prototype._expandRectByRootMargin=function(rect){var margins=this._rootMarginValues.map(function(margin,i){return margin.unit==='px'?margin.value:margin.value*(i%2?rect.width:rect.height)/ 100;}),newRect={top:rect.top-margins[0],right:rect.right+margins[1],bottom:rect.bottom+margins[2],left:rect.left-margins[3]};newRect.width=newRect.right-newRect.left;newRect.height=newRect.bottom-newRect.top;return newRect;};IntersectionObserver.prototype._hasCrossedThreshold=function(oldEntry,newEntry){var oldRatio=oldEntry&&oldEntry.isIntersecting?oldEntry.intersectionRatio||0:-1,newRatio=newEntry.isIntersecting?newEntry.intersectionRatio||0:-1,threshold,i=0;if(oldRatio===newRatio){return;}
for(i;i<this.thresholds.length;i++){threshold=this.thresholds[i];if(threshold==oldRatio||threshold==newRatio||threshold<oldRatio!==threshold<newRatio){return true;}}};IntersectionObserver.prototype._rootIsInDom=function(){return!this.root||containsDeep(document,this.root);};IntersectionObserver.prototype._rootContainsTarget=function(target){return containsDeep(this.root||document,target);};IntersectionObserver.prototype._registerInstance=function(){if(registry.indexOf(this)<0){registry.push(this);}};IntersectionObserver.prototype._unregisterInstance=function(){var index=registry.indexOf(this);if(index!==-1){registry.splice(index,1);}};window.IntersectionObserver=IntersectionObserver;window.IntersectionObserverEntry=IntersectionObserverEntry;}(window,document));