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;(function ()
{
"use strict";
BX.namespace("BX.Landing");
BX.Landing.NavbarScrollSpy = function ()
{
this.links = {};
/**
* @type {HTMLElement[]}
*/
this.targets = [];
/**
* Targets then now in viewport
* @type {HTMLElement[]}
*/
this.onScreen = [];
/**
* To save target ID when click on link
* @type {string}
*/
this.forceHighlightId = null;
this.observer = new IntersectionObserver(
BX.Landing.NavbarScrollSpy.onIntersection,
{threshold: [0.5, 1]}
);
};
// todo: find parent element method may be set by params
BX.Landing.NavbarScrollSpy.CLASS_TO_SET_ACTIVE = 'nav-item';
BX.Landing.NavbarScrollSpy.ACTIVE_CLASS = 'active';
BX.Landing.NavbarScrollSpy.getInstance = function ()
{
return (this.instance || (this.instance = new BX.Landing.NavbarScrollSpy()));
};
/**
* Add navbars from list to scrollSpy
* @param {HTMLElement} scrollspyNode
*/
BX.Landing.NavbarScrollSpy.init = function (scrollspyNode)
{
var scrollSpy = BX.Landing.NavbarScrollSpy.getInstance();
scrollSpy.add(scrollspyNode);
};
BX.Landing.NavbarScrollSpy.onIntersection = function (entries)
{
var scrollspy = BX.Landing.NavbarScrollSpy.getInstance();
entries.forEach(function (entry)
{
scrollspy.checkOnScreen(entry);
});
scrollspy.highlight();
};
BX.Landing.NavbarScrollSpy.getNodeToHighlight = function (linkNode)
{
var nodeToHighlight = BX.findParent(
linkNode,
{
class: BX.Landing.NavbarScrollSpy.CLASS_TO_SET_ACTIVE
}
);
return nodeToHighlight ? nodeToHighlight : linkNode;
};
BX.Landing.NavbarScrollSpy.prototype = {
add: function (scrollspyNode)
{
var links = [].slice.call(scrollspyNode.querySelectorAll('a'));
links.forEach(function (link)
{
if (
link.getAttribute("href") !== "#"
&& link.hash !== ''
&& (link.target === '' || link.target === '_self')
&& link.pathname === document.location.pathname
&& link.hostname === document.location.hostname
)
{
// hash can be not valid for various reasons
try
{
var target = document.querySelector(link.hash);
}
catch (e) {}
if (target)
{
if (typeof this.links[link.hash] === "undefined")
{
this.links[link.hash] = [];
}
this.links[link.hash].push(link);
this.targets.push(target);
this.observer.observe(target);
link.addEventListener("click", BX.delegate(function (event)
{
event.preventDefault();
event.target.blur();
this.forceHighlightId = link.hash;
this.unhighlight();
this.highlightOnce(link.hash);
}, this));
}
}
}, this)
},
/**
* Check which entries now on screen
* @param {IntersectionObserverEntry} entry
*/
checkOnScreen: function (entry)
{
var index = this.onScreen.indexOf(entry.target);
if (entry.isIntersecting && index === -1)
{
this.onScreen.push(entry.target);
}
else if (!entry.isIntersecting && index !== -1)
{
this.onScreen.splice(index, 1);
}
if (
this.forceHighlightId === '#' + entry.target.id
&& !entry.isIntersecting
)
{
this.forceHighlightId = null;
}
},
/**
* Check active target and set .active to corresponding link
*/
highlight: function ()
{
if (this.forceHighlightId !== null)
{
return;
}
this.unhighlight();
var activeTargetId;
var activeTargetPosition;
this.onScreen.forEach(function (target)
{
if (activeTargetPosition === undefined)
{
activeTargetPosition = target.offsetTop;
}
if (target.offsetTop <= activeTargetPosition)
{
activeTargetPosition = target.offsetTop;
activeTargetId = '#' + target.id;
}
}, this);
if (
typeof activeTargetId !== "undefined"
&& typeof this.links[activeTargetId] !== "undefined"
&& this.links[activeTargetId].length > 0
)
{
this.highlightOnce(activeTargetId);
}
},
unhighlight: function ()
{
for (var linkId in this.links)
{
this.unhighlightOnce(linkId);
}
},
highlightOnce: function (linkId)
{
this.links[linkId].forEach(function (link)
{
BX.Landing.NavbarScrollSpy.getNodeToHighlight(link)
.classList.add(BX.Landing.NavbarScrollSpy.ACTIVE_CLASS);
});
},
unhighlightOnce: function (linkId)
{
this.links[linkId].forEach(function (link)
{
BX.Landing.NavbarScrollSpy.getNodeToHighlight(link)
.classList.remove(BX.Landing.NavbarScrollSpy.ACTIVE_CLASS);
}, this)
}
};
})();