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function(){!function(e,t){"use strict";if("IntersectionObserver"in e&&"IntersectionObserverEntry"in e&&"intersectionRatio"in e.IntersectionObserverEntry.prototype){"isIntersecting"in e.IntersectionObserverEntry.prototype||Object.defineProperty(e.IntersectionObserverEntry.prototype,"isIntersecting",{get:function(){return this.intersectionRatio>0}});return}var n=[];function i(e){this.time=e.time,this.target=e.target,this.rootBounds=e.rootBounds,this.boundingClientRect=e.boundingClientRect,this.intersectionRect=e.intersectionRect||l(),this.isIntersecting=!!e.intersectionRect;var t=this.boundingClientRect,n=t.width*t.height,i=this.intersectionRect,r=i.width*i.height;n?this.intersectionRatio=r/n:this.intersectionRatio=+!!this.isIntersecting}function r(e,t){var n,i,r,s=t||{};if("function"!=typeof e)throw Error("callback must be a function");if(s.root&&1!=s.root.nodeType)throw Error("root must be an Element");this._checkForIntersections=(n=this._checkForIntersections.bind(this),i=this.THROTTLE_TIMEOUT,r=null,function(){r||(r=setTimeout(function(){n(),r=null},i))}),this._callback=e,this._observationTargets=[],this._queuedEntries=[],this._rootMarginValues=this._parseRootMargin(s.rootMargin),this.thresholds=this._initThresholds(s.threshold),this.root=s.root||null,this.rootMargin=this._rootMarginValues.map(function(e){return e.value+e.unit}).join(" ")}function s(e,t,n,i){"function"==typeof e.addEventListener?e.addEventListener(t,n,i||!1):"function"==typeof e.attachEvent&&e.attachEvent("on"+t,n)}function a(e,t,n,i){"function"==typeof e.removeEventListener?e.removeEventListener(t,n,i||!1):"function"==typeof e.detatchEvent&&e.detatchEvent("on"+t,n)}function o(e){var t;try{t=e.getBoundingClientRect()}catch(e){}return t?(t.width&&t.height||(t={top:t.top,right:t.right,bottom:t.bottom,left:t.left,width:t.right-t.left,height:t.bottom-t.top}),t):l()}function l(){return{top:0,bottom:0,left:0,right:0,width:0,height:0}}function u(e,t){for(var n=t;n;){if(n==e)return!0;n=d(n)}return!1}function d(e){var t=e.parentNode;return t&&11==t.nodeType&&t.host?t.host:t}r.prototype.THROTTLE_TIMEOUT=100,r.prototype.POLL_INTERVAL=null,r.prototype.USE_MUTATION_OBSERVER=!0,r.prototype.observe=function(e){if(!this._observationTargets.some(function(t){return t.element==e})){if(!(e&&1==e.nodeType))throw Error("target must be an Element");this._registerInstance(),this._observationTargets.push({element:e,entry:null}),this._monitorIntersections(),this._checkForIntersections()}},r.prototype.unobserve=function(e){this._observationTargets=this._observationTargets.filter(function(t){return t.element!=e}),this._observationTargets.length||(this._unmonitorIntersections(),this._unregisterInstance())},r.prototype.disconnect=function(){this._observationTargets=[],this._unmonitorIntersections(),this._unregisterInstance()},r.prototype.takeRecords=function(){var e=this._queuedEntries.slice();return this._queuedEntries=[],e},r.prototype._initThresholds=function(e){var t=e||[0];return Array.isArray(t)||(t=[t]),t.sort().filter(function(e,t,n){if("number"!=typeof e||isNaN(e)||e<0||e>1)throw Error("threshold must be a number between 0 and 1 inclusively");return e!==n[t-1]})},r.prototype._parseRootMargin=function(e){var t=(e||"0px").split(/\s+/).map(function(e){var t=/^(-?\d*\.?\d+)(px|%)$/.exec(e);if(!t)throw Error("rootMargin must be specified in pixels or percent");return{value:parseFloat(t[1]),unit:t[2]}});return t[1]=t[1]||t[0],t[2]=t[2]||t[0],t[3]=t[3]||t[1],t},r.prototype._monitorIntersections=function(){!this._monitoringIntersections&&(this._monitoringIntersections=!0,this.POLL_INTERVAL?this._monitoringInterval=setInterval(this._checkForIntersections,this.POLL_INTERVAL):(s(e,"resize",this._checkForIntersections,!0),s(t,"scroll",this._checkForIntersections,!0),this.USE_MUTATION_OBSERVER&&"MutationObserver"in e&&(this._domObserver=new MutationObserver(this._checkForIntersections),this._domObserver.observe(t,{attributes:!0,childList:!0,characterData:!0,subtree:!0}))))},r.prototype._unmonitorIntersections=function(){this._monitoringIntersections&&(this._monitoringIntersections=!1,clearInterval(this._monitoringInterval),this._monitoringInterval=null,a(e,"resize",this._checkForIntersections,!0),a(t,"scroll",this._checkForIntersections,!0),this._domObserver&&(this._domObserver.disconnect(),this._domObserver=null))},r.prototype._checkForIntersections=function(){var t=this._rootIsInDom(),n=t?this._getRootRect():l();this._observationTargets.forEach(function(r){var s=r.element,a=o(s),l=this._rootContainsTarget(s),u=r.entry,d=t&&l&&this._computeTargetAndRootIntersection(s,n),c=r.entry=new i({time:e.performance&&performance.now&&performance.now(),target:s,boundingClientRect:a,rootBounds:n,intersectionRect:d});u?t&&l?this._hasCrossedThreshold(u,c)&&this._queuedEntries.push(c):u&&u.isIntersecting&&this._queuedEntries.push(c):this._queuedEntries.push(c)},this),this._queuedEntries.length&&this._callback(this.takeRecords(),this)},r.prototype._computeTargetAndRootIntersection=function(n,i){if("none"!=e.getComputedStyle(n).display){for(var r=o(n),s=d(n),a=!1;!a;){var l=null,u=1==s.nodeType?e.getComputedStyle(s):{};if("none"==u.display)return;if(s==this.root||s==t?(a=!0,l=i):s!=t.body&&s!=t.documentElement&&"visible"!=u.overflow&&(l=o(s)),l&&!(r=function(e,t){var n=Math.max(e.top,t.top),i=Math.min(e.bottom,t.bottom),r=Math.max(e.left,t.left),s=Math.min(e.right,t.right),a=s-r,o=i-n;return a>=0&&o>=0&&{top:n,bottom:i,left:r,right:s,width:a,height:o}}(l,r)))break;s=d(s)}return r}},r.prototype._getRootRect=function(){var e;if(this.root)e=o(this.root);else{var n=t.documentElement,i=t.body;e={top:0,left:0,right:n.clientWidth||i.clientWidth,width:n.clientWidth||i.clientWidth,bottom:n.clientHeight||i.clientHeight,height:n.clientHeight||i.clientHeight}}return this._expandRectByRootMargin(e)},r.prototype._expandRectByRootMargin=function(e){var t=this._rootMarginValues.map(function(t,n){return"px"==t.unit?t.value:t.value*(n%2?e.width:e.height)/100}),n={top:e.top-t[0],right:e.right+t[1],bottom:e.bottom+t[2],left:e.left-t[3]};return n.width=n.right-n.left,n.height=n.bottom-n.top,n},r.prototype._hasCrossedThreshold=function(e,t){var n=e&&e.isIntersecting?e.intersectionRatio||0:-1,i=t.isIntersecting?t.intersectionRatio||0:-1;if(n!==i)for(var r=0;r<this.thresholds.length;r++){var s=this.thresholds[r];if(s==n||s==i||s<n!=s<i)return!0}},r.prototype._rootIsInDom=function(){return!this.root||u(t,this.root)},r.prototype._rootContainsTarget=function(e){return u(this.root||t,e)},r.prototype._registerInstance=function(){0>n.indexOf(this)&&n.push(this)},r.prototype._unregisterInstance=function(){var e=n.indexOf(this);-1!=e&&n.splice(e,1)},e.IntersectionObserver=r,e.IntersectionObserverEntry=i}(window,document)}