accordion-item.tsx

import { Component, Prop, State, Element, h } from '@stencil/core';

@Component({
  tag: 'hy-accordion-item',
  styleUrl: 'accordion-item.scss',
  shadow: false
})

export class AccordionItem {
  @Element() el: HTMLElement;
  @Prop() accordiontitle?: string;
  @State() ready: boolean = false;

  componentDidLoad() {
    this.ready = true;
  }

  render() {
    const containerId = this.el.parentElement.id;
    function collapseSection(element) {
      element.style.height = 0 + 'px';
      element.setAttribute('data-collapsed', 'true');
    }
    
    function expandSection(element) {
      element.style.height = element.scrollHeight + 'px';      
      element.setAttribute('data-collapsed', 'false');
    }

    if (this.ready && containerId.length > 0) {
      document.querySelectorAll(`#${containerId}`).forEach(function (accordion) {
        const allowMultiple = accordion.hasAttribute('data-allow-multiple');
        const allowToggle = (allowMultiple) ? allowMultiple : accordion.hasAttribute('data-allow-toggle');
        
        const triggers = Array.prototype.slice.call(accordion.querySelectorAll('.hy-accordion__button'));

        accordion.addEventListener('click', function (event) {
          let target = event.target as HTMLTextAreaElement;

          if (target && target.classList.contains('hy-accordion__button')) {
            let targetParent = target.closest('.hy-accordion__item');
            let targetContent = targetParent.querySelectorAll('.hy-accordion__content')[0];
            const isExpanded = target.getAttribute('aria-expanded') == 'true';
            const active = accordion.querySelector('[aria-expanded="true"]');

            if (!allowMultiple && active && active !== target) {
              active.setAttribute('aria-expanded', 'false');
              collapseSection(targetContent);
              if (targetParent.classList.contains('hy-accordion__item__is-open')) {
                targetParent.classList.remove('hy-accordion__item__is-open');
              }
              accordion.querySelector(`#${active.getAttribute('aria-controls')}`).setAttribute('aria-hidden', 'true');
      
              if (!allowToggle) {
                active.removeAttribute('aria-disabled');
              }
            }
      
            if (!isExpanded) {
              expandSection(targetContent);
              target.setAttribute('aria-expanded', 'true');
              targetParent.classList.add('hy-accordion__item__is-open');

              accordion.querySelector(`#${target.getAttribute('aria-controls')}`).setAttribute('aria-hidden', 'false');
      
              if (!allowToggle) {
                target.setAttribute('aria-disabled', 'true');
              }
            }
            else if (allowToggle && isExpanded) {
              target.setAttribute('aria-expanded', 'false');
              collapseSection(targetContent);
              if (targetParent.classList.contains('hy-accordion__item__is-open')) {
                targetParent.classList.remove('hy-accordion__item__is-open');
              }
              accordion.querySelector(`#${target.getAttribute('aria-controls')}`).setAttribute('aria-hidden', 'true');
            }
      
            event.preventDefault();
            event.stopImmediatePropagation();
          }
        });
      
        if (accordion) {
          accordion.addEventListener('keydown', function (event: KeyboardEvent) {
            const target = event.target as HTMLButtonElement;
            const key = event.which.toString();
        
            // 33 = Page Up, 34 = Page Down
            const ctrlModifier = (event.ctrlKey && key.match(/33|34/));

            if (target.classList.contains('hy-accordion__button')) {
              // Up/ Down arrow and Control + Page Up/ Page Down keyboard operations
              // 38 = Up, 40 = Down
              if (key.match(/38|40/) || ctrlModifier) {
                const index = triggers.indexOf(target);
                const direction = (key.match(/34|40/)) ? 1 : -1;
                const length = triggers.length;
                const newIndex = (index + length + direction) % length;
                triggers[newIndex].focus();
        
                event.preventDefault();
              }
              else if (key.match(/35|36/)) {
                // 35 = End, 36 = Home keyboard operations
                switch (key) {
                  // Go to first accordion
                  case '36':
                    triggers[0].focus();
                    break;
                    // Go to last accordion
                  case '35':
                    triggers[triggers.length - 1].focus();
                    break;
                }
                event.preventDefault();
              }
            }
          });
        
          accordion.querySelectorAll('.hy-accordion__button').forEach(function (trigger) {
            trigger.addEventListener('focus', function () {
              trigger.classList.add('focus');
            });
            trigger.addEventListener('blur', function () {
              trigger.classList.remove('focus');
            });
          });
        }
      });
    }

    const classAttributes = ["hy-accordion__item"];
    const titleAsId = this.accordiontitle.toLowerCase().replace(/\W/g,'-');
    return (
      <div class={classAttributes.join(" ")}>
        <div class="hy-accordion--heading">
          <button
            aria-expanded="false"
            aria-controls={`${titleAsId}--content`}
            class="hy-accordion__button"
            id={`${titleAsId}--title`}
          >
            <span class="hy-accordion--heading__icon">
              <hy-icon icon={'hy-icon-caret-down'} size={16} />
            </span>
            { this.accordiontitle }
          </button>
        </div>
        <div
          aria-labelledBy={`${titleAsId}--title`}
          class="hy-accordion__content"
          id={`${titleAsId}--content`}
          role="region"
        >
          <div class="hy-accordion__content--inner-wrapper">
            <slot></slot>
          </div>
        </div>
      </div>
    );
  }

}