(function(){'use strict';if(typeof window!=='object'){return;}
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 getFrameElement(doc){try{return doc.defaultView&&doc.defaultView.frameElement||null;}catch(e){return null;}}
var document=(function(startDoc){var doc=startDoc;var frame=getFrameElement(doc);while(frame){doc=frame.ownerDocument;frame=getFrameElement(doc);}
return doc;})(window.document);var registry=[];var crossOriginUpdater=null;var crossOriginRect=null;function IntersectionObserverEntry(entry){this.time=entry.time;this.target=entry.target;this.rootBounds=ensureDOMRect(entry.rootBounds);this.boundingClientRect=ensureDOMRect(entry.boundingClientRect);this.intersectionRect=ensureDOMRect(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&&options.root.nodeType!=9){throw new Error('root must be a Document or 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(' ');this._monitoringDocuments=[];this._monitoringUnsubscribes=[];}
IntersectionObserver.prototype.THROTTLE_TIMEOUT=100;IntersectionObserver.prototype.POLL_INTERVAL=null;IntersectionObserver.prototype.USE_MUTATION_OBSERVER=true;IntersectionObserver._setupCrossOriginUpdater=function(){if(!crossOriginUpdater){crossOriginUpdater=function(boundingClientRect,intersectionRect){if(!boundingClientRect||!intersectionRect){crossOriginRect=getEmptyRect();}else{crossOriginRect=convertFromParentRect(boundingClientRect,intersectionRect);}
registry.forEach(function(observer){observer._checkForIntersections();});};}
return crossOriginUpdater;};IntersectionObserver._resetCrossOriginUpdater=function(){crossOriginUpdater=null;crossOriginRect=null;};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(target.ownerDocument);this._checkForIntersections();};IntersectionObserver.prototype.unobserve=function(target){this._observationTargets=this._observationTargets.filter(function(item){return item.element!=target;});this._unmonitorIntersections(target.ownerDocument);if(this._observationTargets.length==0){this._unregisterInstance();}};IntersectionObserver.prototype.disconnect=function(){this._observationTargets=[];this._unmonitorAllIntersections();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(doc){var win=doc.defaultView;if(!win){return;}
if(this._monitoringDocuments.indexOf(doc)!=-1){return;}
var callback=this._checkForIntersections;var monitoringInterval=null;var domObserver=null;if(this.POLL_INTERVAL){monitoringInterval=win.setInterval(callback,this.POLL_INTERVAL);}else{addEvent(win,'resize',callback,true);addEvent(doc,'scroll',callback,true);if(this.USE_MUTATION_OBSERVER&&'MutationObserver'in win){domObserver=new win.MutationObserver(callback);domObserver.observe(doc,{attributes:true,childList:true,characterData:true,subtree:true});}}
this._monitoringDocuments.push(doc);this._monitoringUnsubscribes.push(function(){var win=doc.defaultView;if(win){if(monitoringInterval){win.clearInterval(monitoringInterval);}
removeEvent(win,'resize',callback,true);}
removeEvent(doc,'scroll',callback,true);if(domObserver){domObserver.disconnect();}});var rootDoc=(this.root&&(this.root.ownerDocument||this.root))||document;if(doc!=rootDoc){var frame=getFrameElement(doc);if(frame){this._monitorIntersections(frame.ownerDocument);}}};IntersectionObserver.prototype._unmonitorIntersections=function(doc){var index=this._monitoringDocuments.indexOf(doc);if(index==-1){return;}
var rootDoc=(this.root&&(this.root.ownerDocument||this.root))||document;var hasDependentTargets=this._observationTargets.some(function(item){var itemDoc=item.element.ownerDocument;if(itemDoc==doc){return true;}
while(itemDoc&&itemDoc!=rootDoc){var frame=getFrameElement(itemDoc);itemDoc=frame&&frame.ownerDocument;if(itemDoc==doc){return true;}}
return false;});if(hasDependentTargets){return;}
var unsubscribe=this._monitoringUnsubscribes[index];this._monitoringDocuments.splice(index,1);this._monitoringUnsubscribes.splice(index,1);unsubscribe();if(doc!=rootDoc){var frame=getFrameElement(doc);if(frame){this._unmonitorIntersections(frame.ownerDocument);}}};IntersectionObserver.prototype._unmonitorAllIntersections=function(){var unsubscribes=this._monitoringUnsubscribes.slice(0);this._monitoringDocuments.length=0;this._monitoringUnsubscribes.length=0;for(var i=0;i<unsubscribes.length;i++){unsubscribes[i]();}};IntersectionObserver.prototype._checkForIntersections=function(){if(!this.root&&crossOriginUpdater&&!crossOriginRect){return;}
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,targetRect,rootRect);var rootBounds=null;if(!this._rootContainsTarget(target)){rootBounds=getEmptyRect();}else if(!crossOriginUpdater||this.root){rootBounds=rootRect;}
var newEntry=item.entry=new IntersectionObserverEntry({time:now(),target:target,boundingClientRect:targetRect,rootBounds:rootBounds,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,targetRect,rootRect){if(window.getComputedStyle(target).display=='none')return;var intersectionRect=targetRect;var parent=getParentNode(target);var atRoot=false;while(!atRoot&&parent){var parentRect=null;var parentComputedStyle=parent.nodeType==1?window.getComputedStyle(parent):{};if(parentComputedStyle.display=='none')return null;if(parent==this.root||parent.nodeType==9){atRoot=true;if(parent==this.root||parent==document){if(crossOriginUpdater&&!this.root){if(!crossOriginRect||crossOriginRect.width==0&&crossOriginRect.height==0){parent=null;parentRect=null;intersectionRect=null;}else{parentRect=crossOriginRect;}}else{parentRect=rootRect;}}else{var frame=getParentNode(parent);var frameRect=frame&&getBoundingClientRect(frame);var frameIntersect=frame&&this._computeTargetAndRootIntersection(frame,frameRect,rootRect);if(frameRect&&frameIntersect){parent=frame;parentRect=convertFromParentRect(frameRect,frameIntersect);}else{parent=null;intersectionRect=null;}}}else{var doc=parent.ownerDocument;if(parent!=doc.body&&parent!=doc.documentElement&&parentComputedStyle.overflow!='visible'){parentRect=getBoundingClientRect(parent);}}
if(parentRect){intersectionRect=computeRectIntersection(parentRect,intersectionRect);}
if(!intersectionRect)break;parent=parent&&getParentNode(parent);}
return intersectionRect;};IntersectionObserver.prototype._getRootRect=function(){var rootRect;if(this.root&&!isDoc(this.root)){rootRect=getBoundingClientRect(this.root);}else{var doc=isDoc(this.root)?this.root:document;var html=doc.documentElement;var body=doc.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 true;}}};IntersectionObserver.prototype._rootIsInDom=function(){return!this.root||containsDeep(document,this.root);};IntersectionObserver.prototype._rootContainsTarget=function(target){var rootDoc=(this.root&&(this.root.ownerDocument||this.root))||document;return(containsDeep(rootDoc,target)&&(!this.root||rootDoc==target.ownerDocument));};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||false);}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||false);}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}||null;}
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 ensureDOMRect(rect){if(!rect||'x'in rect){return rect;}
return{top:rect.top,y:rect.top,bottom:rect.bottom,left:rect.left,x:rect.left,right:rect.right,width:rect.width,height:rect.height};}
function convertFromParentRect(parentBoundingRect,parentIntersectionRect){var top=parentIntersectionRect.top-parentBoundingRect.top;var left=parentIntersectionRect.left-parentBoundingRect.left;return{top:top,left:left,height:parentIntersectionRect.height,width:parentIntersectionRect.width,bottom:top+parentIntersectionRect.height,right:left+parentIntersectionRect.width};}
function containsDeep(parent,child){var node=child;while(node){if(node==parent)return true;node=getParentNode(node);}
return false;}
function getParentNode(node){var parent=node.parentNode;if(node.nodeType==9&&node!=document){return getFrameElement(node);}
if(parent&&parent.assignedSlot){parent=parent.assignedSlot.parentNode}
if(parent&&parent.nodeType==11&&parent.host){return parent.host;}
return parent;}
function isDoc(node){return node&&node.nodeType===9;}
window.IntersectionObserver=IntersectionObserver;window.IntersectionObserverEntry=IntersectionObserverEntry;}());