Build Responsive Accordions With Vanilla JS And CSS3

A tiny JavaScript library that helps you create responsive collapsing accordion elements using plain JavaScript and CSS. Ideal for FAQs, tabs, and show/hide UIs.

The accordion library leverages the benefits of CSS Flexbox for fluid layout control, coupled with CSS3 transitions and transforms to deliver sleek expand/collapse animations.

How to use it:

1. The required HTML structure for the accordion UI.

<div class="vnl-accordions">
  <div class="vnl-accordions-item">
    <h3 class="vnl-accordions-title">FAQ 1</h3>
    <div class="vnl-accordions-content">
      <p>
        Answer 1
      </p>
    </div>
    <div class="vnl-accordions-action"></div>
  </div>
  <div class="vnl-accordions-item">
    <h3 class="vnl-accordions-title">FAQ 2</h3>
    <div class="vnl-accordions-content">
      <p>
       Answer 2
      </p>
    </div>
    <div class="vnl-accordions-action"></div>
  </div>
  ... more FAQ here ..
</div>

2. Download and load the vanilla-accordions.js script at the end of the document.

<script src="js/vanilla-accordions.js"></script>

3. The example CSS for the accoridon.

.vnl-accordions {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  --tw-bg-opacity: 1;
  background-color: rgb(57 54 70 / var(--tw-bg-opacity));
  padding: 1rem;
  --tw-text-opacity: 1;
  color: rgb(127 132 135 / var(--tw-text-opacity));
  font-family: 'Lato', sans-serif;
}
.vnl-accordions-item {
  position: relative;
  cursor: pointer;
  border-radius: 0.5rem;
  border-width: 1px;
  border-color: transparent;
  padding-left: 0px;
  padding-right: 0px;
  padding-left: 1rem;
  padding-right: 4rem;
}
.vnl-accordions-item:hover {
  background-color: rgba(0, 0, 0, .1);
}
.vnl-accordions-item.active .vnl-accordions-title {
  --tw-text-opacity: 1;
  color: rgb(236 179 101 / var(--tw-text-opacity));
}
.vnl-accordions-item.active .vnl-accordions-content {
  max-height: 900px;
}
.vnl-accordions-item.active .vnl-accordions-action {
  transform: rotate(45deg);
}
.vnl-accordions-item.active .vnl-accordions-action:before,
.vnl-accordions-item.active .vnl-accordions-action:after {
  --tw-bg-opacity: 1;
  background-color: rgb(236 179 101 / var(--tw-bg-opacity));
}
.vnl-accordions-title {
  margin-top: 1rem;
  margin-bottom: 1rem;
  font-size: 1.875rem;
  font-weight: 300;
}
.vnl-accordions-content {
  overflow: hidden;
  max-height: 0;
  transition: max-height .25s;
}
.vnl-accordions-content p {
  margin-bottom: 1rem;
  line-height: 2;
}
.vnl-accordions-action {
  position: absolute;
  top: 1.75rem;
  right: 1.75rem;
  display: block;
  height: 1.25rem;
  width: 1.25rem;
  transition: transform .3s;
}
.vnl-accordions-action:before,
.vnl-accordions-action:after {
  position: absolute;
  display: block;
  width: 100%;
  --tw-bg-opacity: 1;
  background-color: rgb(127 132 135 / var(--tw-bg-opacity));
  content: '';
  height: 1px;
  left: 50%;
  top: 50%;
}
.vnl-accordions-action:before {
  transform: translate(-50%, -50%);
}
.vnl-accordions-action:after {
  transform: translate(-50%, -50%) rotate(90deg);
}