How to create Accordion custom element in web component

Question

I am trying to create an Accordion using the custom element in javascript.

the below mentioned HTML as I have written in the HTML

var accordions = document.querySelectorAll(".accordion");

for (var i = 0; i < accordions.length; i++) {
  accordions[i].onclick = function () {
    this.classList.toggle('is-open');
    var content = this.nextElementSibling;
    if (content.style.maxHeight) {
      content.style.maxHeight = null;
    } else {
      content.style.maxHeight = content.scrollHeight + "px";
    }
  }
}

<div class="container">
  <button class="accordion">Accordian #1</button>
  <div class="accordion-content">
    <p> Content 1</p>
  </div>
</div>

this code how to create using the custom element?

Answer 1

If you can create a Modern Custom Element/Web Component <my-accordion> ,
using the Browser native <details> and <summary> elements

• https://developer.mozilla.org/en-US/docs/Web/HTML/Element/details
• https://css-tricks.com/quick-reminder-that-details-summary-is-the-easiest-way-ever-to-make-an-accordion/

<style>
  summary {
    cursor: pointer;
    font-size: 1.2em;
    margin-bottom: .5em;
  }
  details[open] {
    background: lightgreen;
    padding-left: 1em;
  }
  details[open] summary {
    background: green;
    color: white;
    margin-left: -1em;
  }
</style>
<my-accordion>
  <details><summary>Alpha</summary>Amazing!</details>
  <details open><summary>Bravo</summary>Note the default open attribute</details>
  <details><summary>Charlie</summary><h3>Cool!</h3>hold Ctrl Key</details>
  <details><summary>Delta</summary><B>D...</B><hr>The end</details>
</my-accordion>
<script>
  customElements.define('my-accordion', class extends HTMLElement {
    connectedCallback() {
      this.onclick = evt => {
        [...this.children].map(detail => {
          !evt.ctrlKey && detail.toggleAttribute("open", evt.target == detail);
        });
      }
    }
  });
</script>

Note: There is a toggle Event you can try (with useCapture=true), but toggleAttribute will trigger that Event! Causing a nice endless loop

Dev.to Blog Post: The Accordion Web Component