(function(window,document){'use strict';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}
var registry=[];function IntersectionObserverEntry(entry){this.time=entry.time;this.target=entry.target;this.rootBounds=entry.rootBounds;this.boundingClientRect=entry.boundingClientRect;this.intersectionRect=entry.intersectionRect||getEmptyRect();this.isIntersecting=!!entry.intersectionRect;var targetRect=this.boundingClientRect;var targetArea=targetRect.width*targetRect.height;var intersectionRect=this.intersectionRect;var intersectionArea=intersectionRect.width*intersectionRect.height;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&&options.root.nodeType!=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=!0;IntersectionObserver.prototype.observe=function(target){var isTargetAlreadyObserved=this._observationTargets.some(function(item){return item.element==target});if(isTargetAlreadyObserved){return}
if(!(target&&target.nodeType==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';var 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){this._monitoringIntersections=!0;if(this.POLL_INTERVAL){this._monitoringInterval=setInterval(this._checkForIntersections,this.POLL_INTERVAL)}else{addEvent(window,'resize',this._checkForIntersections,!0);addEvent(document,'scroll',this._checkForIntersections,!0);if(this.USE_MUTATION_OBSERVER&&'MutationObserver' in window){this._domObserver=new MutationObserver(this._checkForIntersections);this._domObserver.observe(document,{attributes:!0,childList:!0,characterData:!0,subtree:!0})}}}};IntersectionObserver.prototype._unmonitorIntersections=function(){if(this._monitoringIntersections){this._monitoringIntersections=!1;clearInterval(this._monitoringInterval);this._monitoringInterval=null;removeEvent(window,'resize',this._checkForIntersections,!0);removeEvent(document,'scroll',this._checkForIntersections,!0);if(this._domObserver){this._domObserver.disconnect();this._domObserver=null}}};IntersectionObserver.prototype._checkForIntersections=function(){var rootIsInDom=this._rootIsInDom();var rootRect=rootIsInDom?this._getRootRect():getEmptyRect();this._observationTargets.forEach(function(item){var target=item.element;var targetRect=getBoundingClientRect(target);var rootContainsTarget=this._rootContainsTarget(target);var oldEntry=item.entry;var intersectionRect=rootIsInDom&&rootContainsTarget&&this._computeTargetAndRootIntersection(target,rootRect);var 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){if(window.getComputedStyle(target).display=='none')return;var targetRect=getBoundingClientRect(target);var intersectionRect=targetRect;var parent=getParentNode(target);var atRoot=!1;while(!atRoot){var parentRect=null;var parentComputedStyle=parent.nodeType==1?window.getComputedStyle(parent):{};if(parentComputedStyle.display=='none')return;if(parent==this.root||parent==document){atRoot=!0;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;if(this.root){rootRect=getBoundingClientRect(this.root)}else{var html=document.documentElement;var 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});var 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;var newRatio=newEntry.isIntersecting?newEntry.intersectionRatio||0:-1;if(oldRatio===newRatio)return;for(var i=0;i<this.thresholds.length;i++){var threshold=this.thresholds[i];if(threshold==oldRatio||threshold==newRatio||threshold<oldRatio!==threshold<newRatio){return!0}}};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);};function now(){return window.performance&&performance.now&&performance.now()}
function throttle(fn,timeout){var timer=null;return function(){if(!timer){timer=setTimeout(function(){fn();timer=null},timeout)}}}
function addEvent(node,event,fn,opt_useCapture){if(typeof node.addEventListener=='function'){node.addEventListener(event,fn,opt_useCapture||!1)}else if(typeof node.attachEvent=='function'){node.attachEvent('on'+event,fn)}}
function removeEvent(node,event,fn,opt_useCapture){if(typeof node.removeEventListener=='function'){node.removeEventListener(event,fn,opt_useCapture||!1)}else if(typeof node.detatchEvent=='function'){node.detatchEvent('on'+event,fn)}}
function computeRectIntersection(rect1,rect2){var top=Math.max(rect1.top,rect2.top);var bottom=Math.min(rect1.bottom,rect2.bottom);var left=Math.max(rect1.left,rect2.left);var right=Math.min(rect1.right,rect2.right);var width=right-left;var height=bottom-top;return(width>=0&&height>=0)&&{top:top,bottom:bottom,left:left,right:right,width:width,height:height}}
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 getEmptyRect(){return{top:0,bottom:0,left:0,right:0,width:0,height:0}}
function containsDeep(parent,child){var node=child;while(node){if(node==parent)return!0;node=getParentNode(node)}
return!1}
function getParentNode(node){var parent=node.parentNode;if(parent&&parent.nodeType==11&&parent.host){return parent.host}
if(parent&&parent.assignedSlot){return parent.assignedSlot.parentNode}
return parent}
window.IntersectionObserver=IntersectionObserver;window.IntersectionObserverEntry=IntersectionObserverEntry}(window,document))