accordion

by Richard Hunter

HTML

<div class="accordion">
  <div class="header">
    alpha
  </div>
  <div class="main">
    <div class="content">
      orem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore</div>
  </div>
</div>

<div class="container">

  <div class="accordion">
    <div class="header">
      beta
    </div>
    <div class="main">
      <div class="content">
        orem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore</div>
    </div>
  </div>
  <div class="accordion">
    <div class="header">
      gamma
    </div>
    <div class="main">
      <div class="content">
        orem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore</div>
    </div>
  </div>

</div>

CSS

html {
  box-sizing: border-box;
}
*, *:before, *:after {
  box-sizing: inherit;
}

.container {
  background: lightblue;
  height: 400px;
}

.accordion {
  background: pink;
  
}

.header {
  background: antiquewhite;
  padding: 10px;
}

.main {
  background: navajowhite;
  overflow: hidden;
}

.content {
  padding: 10px;
}

JavaScript

const headers = document.querySelectorAll('.header');

headers.forEach((headerEl) => {
  let open = false;
  const mainEl = headerEl.parentElement.children[1];
  mainEl.style.height = 0;
  mainEl.style.transition = 'linear 0.4s height';

  headerEl.addEventListener('click', () => {
    open = !open;

    if (open) {
      mainEl.style.height = 'auto';
      const height = mainEl.offsetHeight;
      mainEl.style.height = 0;
      mainEl.offsetWidth;
      mainEl.style.height = height + 'px';
    } else {
      mainEl.style.height = 0;
    }
  });
});