/*!
  * Bootstrap scrollspy.js v5.3.0-alpha1 (https://getbootstrap.com/)
  * Copyright 2011-2022 The Bootstrap Authors (https://github.com/twbs/bootstrap/graphs/contributors)
  * Licensed under MIT (https://github.com/twbs/bootstrap/blob/main/LICENSE)
  */
(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory(require('./util/index.js'), require('./dom/event-handler.js'), require('./dom/selector-engine.js'), require('./base-component.js')) :
  typeof define === 'function' && define.amd ? define(['./util/index', './dom/event-handler', './dom/selector-engine', './base-component'], factory) :
  (global = typeof globalThis !== 'undefined' ? globalThis : global || self, global.Scrollspy = factory(global.Index, global.EventHandler, global.SelectorEngine, global.BaseComponent));
})(this, (function (index_js, EventHandler, SelectorEngine, BaseComponent) { 'use strict';

  /**
   * --------------------------------------------------------------------------
   * Bootstrap (v5.3.0-alpha1): scrollspy.js
   * Licensed under MIT (https://github.com/twbs/bootstrap/blob/main/LICENSE)
   * --------------------------------------------------------------------------
   */

  /**
   * Constants
   */

  const NAME = 'scrollspy';
  const DATA_KEY = 'bs.scrollspy';
  const EVENT_KEY = `.${DATA_KEY}`;
  const DATA_API_KEY = '.data-api';
  const EVENT_ACTIVATE = `activate${EVENT_KEY}`;
  const EVENT_CLICK = `click${EVENT_KEY}`;
  const EVENT_LOAD_DATA_API = `load${EVENT_KEY}${DATA_API_KEY}`;
  const CLASS_NAME_DROPDOWN_ITEM = 'dropdown-item';
  const CLASS_NAME_ACTIVE = 'active';
  const SELECTOR_DATA_SPY = '[data-bs-spy="scroll"]';
  const SELECTOR_TARGET_LINKS = '[href]';
  const SELECTOR_NAV_LIST_GROUP = '.nav, .list-group';
  const SELECTOR_NAV_LINKS = '.nav-link';
  const SELECTOR_NAV_ITEMS = '.nav-item';
  const SELECTOR_LIST_ITEMS = '.list-group-item';
  const SELECTOR_LINK_ITEMS = `${SELECTOR_NAV_LINKS}, ${SELECTOR_NAV_ITEMS} > ${SELECTOR_NAV_LINKS}, ${SELECTOR_LIST_ITEMS}`;
  const SELECTOR_DROPDOWN = '.dropdown';
  const SELECTOR_DROPDOWN_TOGGLE = '.dropdown-toggle';
  const Default = {
    offset: null,
    // TODO: v6 @deprecated, keep it for backwards compatibility reasons
    rootMargin: '0px 0px -25%',
    smoothScroll: false,
    target: null,
    threshold: [0.1, 0.5, 1]
  };
  const DefaultType = {
    offset: '(number|null)',
    // TODO v6 @deprecated, keep it for backwards compatibility reasons
    rootMargin: 'string',
    smoothScroll: 'boolean',
    target: 'element',
    threshold: 'array'
  };

  /**
   * Class definition
   */

  class ScrollSpy extends BaseComponent {
    constructor(element, config) {
      super(element, config);

      // this._element is the observablesContainer and config.target the menu links wrapper
      this._targetLinks = new Map();
      this._observableSections = new Map();
      this._rootElement = getComputedStyle(this._element).overflowY === 'visible' ? null : this._element;
      this._activeTarget = null;
      this._observer = null;
      this._previousScrollData = {
        visibleEntryTop: 0,
        parentScrollTop: 0
      };
      this.refresh(); // initialize
    }

    // Getters
    static get Default() {
      return Default;
    }
    static get DefaultType() {
      return DefaultType;
    }
    static get NAME() {
      return NAME;
    }

    // Public
    refresh() {
      this._initializeTargetsAndObservables();
      this._maybeEnableSmoothScroll();
      if (this._observer) {
        this._observer.disconnect();
      } else {
        this._observer = this._getNewObserver();
      }
      for (const section of this._observableSections.values()) {
        this._observer.observe(section);
      }
    }
    dispose() {
      this._observer.disconnect();
      super.dispose();
    }

    // Private
    _configAfterMerge(config) {
      // TODO: on v6 target should be given explicitly & remove the {target: 'ss-target'} case
      config.target = index_js.getElement(config.target) || document.body;

      // TODO: v6 Only for backwards compatibility reasons. Use rootMargin only
      config.rootMargin = config.offset ? `${config.offset}px 0px -30%` : config.rootMargin;
      if (typeof config.threshold === 'string') {
        config.threshold = config.threshold.split(',').map(value => Number.parseFloat(value));
      }
      return config;
    }
    _maybeEnableSmoothScroll() {
      if (!this._config.smoothScroll) {
        return;
      }

      // unregister any previous listeners
      EventHandler.off(this._config.target, EVENT_CLICK);
      EventHandler.on(this._config.target, EVENT_CLICK, SELECTOR_TARGET_LINKS, event => {
        const observableSection = this._observableSections.get(event.target.hash);
        if (observableSection) {
          event.preventDefault();
          const root = this._rootElement || window;
          const height = observableSection.offsetTop - this._element.offsetTop;
          if (root.scrollTo) {
            root.scrollTo({
              top: height,
              behavior: 'smooth'
            });
            return;
          }

          // Chrome 60 doesn't support `scrollTo`
          root.scrollTop = height;
        }
      });
    }
    _getNewObserver() {
      const options = {
        root: this._rootElement,
        threshold: this._config.threshold,
        rootMargin: this._config.rootMargin
      };
      return new IntersectionObserver(entries => this._observerCallback(entries), options);
    }

    // The logic of selection
    _observerCallback(entries) {
      const targetElement = entry => this._targetLinks.get(`#${entry.target.id}`);
      const activate = entry => {
        this._previousScrollData.visibleEntryTop = entry.target.offsetTop;
        this._process(targetElement(entry));
      };
      const parentScrollTop = (this._rootElement || document.documentElement).scrollTop;
      const userScrollsDown = parentScrollTop >= this._previousScrollData.parentScrollTop;
      this._previousScrollData.parentScrollTop = parentScrollTop;
      for (const entry of entries) {
        if (!entry.isIntersecting) {
          this._activeTarget = null;
          this._clearActiveClass(targetElement(entry));
          continue;
        }
        const entryIsLowerThanPrevious = entry.target.offsetTop >= this._previousScrollData.visibleEntryTop;
        // if we are scrolling down, pick the bigger offsetTop
        if (userScrollsDown && entryIsLowerThanPrevious) {
          activate(entry);
          // if parent isn't scrolled, let's keep the first visible item, breaking the iteration
          if (!parentScrollTop) {
            return;
          }
          continue;
        }

        // if we are scrolling up, pick the smallest offsetTop
        if (!userScrollsDown && !entryIsLowerThanPrevious) {
          activate(entry);
        }
      }
    }
    _initializeTargetsAndObservables() {
      this._targetLinks = new Map();
      this._observableSections = new Map();
      const targetLinks = SelectorEngine.find(SELECTOR_TARGET_LINKS, this._config.target);
      for (const anchor of targetLinks) {
        // ensure that the anchor has an id and is not disabled
        if (!anchor.hash || index_js.isDisabled(anchor)) {
          continue;
        }
        const observableSection = SelectorEngine.findOne(anchor.hash, this._element);

        // ensure that the observableSection exists & is visible
        if (index_js.isVisible(observableSection)) {
          this._targetLinks.set(anchor.hash, anchor);
          this._observableSections.set(anchor.hash, observableSection);
        }
      }
    }
    _process(target) {
      if (this._activeTarget === target) {
        return;
      }
      this._clearActiveClass(this._config.target);
      this._activeTarget = target;
      target.classList.add(CLASS_NAME_ACTIVE);
      this._activateParents(target);
      EventHandler.trigger(this._element, EVENT_ACTIVATE, {
        relatedTarget: target
      });
    }
    _activateParents(target) {
      // Activate dropdown parents
      if (target.classList.contains(CLASS_NAME_DROPDOWN_ITEM)) {
        SelectorEngine.findOne(SELECTOR_DROPDOWN_TOGGLE, target.closest(SELECTOR_DROPDOWN)).classList.add(CLASS_NAME_ACTIVE);
        return;
      }
      for (const listGroup of SelectorEngine.parents(target, SELECTOR_NAV_LIST_GROUP)) {
        // Set triggered links parents as active
        // With both <ul> and <nav> markup a parent is the previous sibling of any nav ancestor
        for (const item of SelectorEngine.prev(listGroup, SELECTOR_LINK_ITEMS)) {
          item.classList.add(CLASS_NAME_ACTIVE);
        }
      }
    }
    _clearActiveClass(parent) {
      parent.classList.remove(CLASS_NAME_ACTIVE);
      const activeNodes = SelectorEngine.find(`${SELECTOR_TARGET_LINKS}.${CLASS_NAME_ACTIVE}`, parent);
      for (const node of activeNodes) {
        node.classList.remove(CLASS_NAME_ACTIVE);
      }
    }

    // Static
    static jQueryInterface(config) {
      return this.each(function () {
        const data = ScrollSpy.getOrCreateInstance(this, config);
        if (typeof config !== 'string') {
          return;
        }
        if (data[config] === undefined || config.startsWith('_') || config === 'constructor') {
          throw new TypeError(`No method named "${config}"`);
        }
        data[config]();
      });
    }
  }

  /**
   * Data API implementation
   */

  EventHandler.on(window, EVENT_LOAD_DATA_API, () => {
    for (const spy of SelectorEngine.find(SELECTOR_DATA_SPY)) {
      ScrollSpy.getOrCreateInstance(spy);
    }
  });

  /**
   * jQuery
   */

  index_js.defineJQueryPlugin(ScrollSpy);

  return ScrollSpy;

}));
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