CSS Transitions Not working after toggle between classes-CodePudding

I created a toggle menu, I used my real project source code for it so that there should be no confusion:-

div.btn-dropdown-options {
    font-family: "Haas Grot Text R Web", "Helvetica Neue", Helvetica, Arial, sans-serif;
    font-size: 14px;
    font-weight: 400;
    line-height: 20px;
    
    position: absolute;
    z-index: 1;
    bottom: calc(100%   8px);
    left: 0;
    min-width: 180px;
    margin-top: 4px;

    padding: 8px;
    
    border: 1px solid rgba(0,0,0,0.05);
    border-radius: 8px;
    background: #fff;
    display: none;
    
    -webkit-box-shadow: 0 0 5px 1px rgb(0 0 0 / 10%);
    box-shadow: 0 0 5px 1px rgb(0 0 0 / 10%);
}


full code: - https://jsfiddle.net/bnpehzjw/

I addded a css transition effect for div.btn-dropdown-options, and i used visibility: hidden; to visibility: visible;.

When I click the menu toggle to show the menu, the transition works well. But when I click the menu toggle to hide the menu again the transition doesn't work.

What did I do wrong?

CodePudding user response：

TL;DR. See the code snippet below which is slightly tweaked from your original code.

A few notes:

Consider using button instead of a tag. It's a button that does something when clicked as opposed to a hyperlink that directs to a link when clicked.
Be careful with overly specific CSS rules. div.button-dropdown-options (i.e. element name class name) is more specific than .button-dropdown-options (i.e. class name only), and can trump other less specific selectors. It is what makes you overly rely on !important in multiple places. Over specificity and !important in combination will make it very hard to debug styling.
visibility as part of transition property as well. That is, something like transition: opacity 2s, visibility 2s;

function showDropDown() {
  const variantButton = document.getElementById('showdropdown');
  const variantMenu = document.getElementById('variantMenu');
  const animate_arrow = document.querySelector('.btn-dropdown-caret');
  const options = document.querySelector('.btn-dropdown-options');
  const over = document.querySelector('.swiper-container');
  const calculatedOptions = window.getComputedStyle(options);

  variantButton.addEventListener('click', function(event) {
    variantMenu.classList.toggle('dropdownShow');
    animate_arrow.classList.toggle('animate-arrow');
  });

}
showDropDown();

.btn-dropdown {
  display: block;
  position: relative;
  white-space: nowrap;
  margin-top: 5px;
  margin-left: 2px;
}

@media screen and (min-width: 768px) {
  .btn-dropdown {
    z-index: 4;
  }
}

.btn-dropdown .btn-dropdown-link {
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
  width: 100%;
}

.form-btn.outlined.btn-dropdown-link {
  font-family: "Haas Grot Text R Web", "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 14px;
  font-weight: 400;
  line-height: 20px;
  /* -webkit-transition: color 200ms ease;
    transition: color 200ms ease; */
  border: 1px solid #dddddd;
  box-shadow: none;
  -webkit-touch-callout: none;
  /* iOS Safari */
  -webkit-user-select: none;
  /* Safari */
  -khtml-user-select: none;
  /* Konqueror HTML */
  -moz-user-select: none;
  /* Old versions of Firefox */
  -ms-user-select: none;
  /* Internet Explorer/Edge */
  user-select: none;
  /* Non-prefixed version, currently */
  transition: all 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94) !important;
  color: #6e6d7a;
}

.form-btn.outlined.btn-dropdown-link:hover,
.form-btn.outlined.btn-dropdown-link:focus {
  border: 1px solid #e4b29b;
  color: #1b1b1b;
  box-shadow: 0 0 0 2px rgb(228 178 155 / 10%);
}

.form-btn.outlined.btn-dropdown-link:hover svg,
.form-btn.outlined.btn-dropdown-link:focus svg {
  fill: #666666;
}

.animate-arrow {
  transition: transform 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  transform: translateY(-50%) rotate(180deg) !important;
}

.form-btn.outlined,
a.form-btn.outlined {
  background-color: transparent;
  -webkit-box-shadow: 0px 0px 0px 1px #e7e7e9 inset;
  box-shadow: 0px 0px 0px 1px #e7e7e9 inset;
  color: #0d0c22;
}

.btn-dropdown .btn-dropdown-link {
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
  padding-right: 35px;
  text-align: left;
}

.form-btn,
a.form-btn {
  background: #f3f3f4;
  color: #0d0c22;
}

.form-btn,
a.form-btn {
  display: inline-block;
  position: relative;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
  height: 40px;
  padding: 10px 16px;
  -webkit-transition: color 200ms ease;
  transition: color 200ms ease;
  border: none;
  border-radius: 10px;
  outline: none;
  background: #ea4c89;
  text-align: center;
  text-decoration: none;
  cursor: pointer;
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
  font-family: "Haas Grot Text R Web", "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 14px;
  font-weight: 500;
  line-height: 20px;
}


/* Variant Selector --Span */

.btn-dropdown.btn-dropdown-neue svg.btn-dropdown-caret {
  fill: #9e9ea7;
}

.btn-dropdown svg.btn-dropdown-caret {
  position: absolute;
  top: 50%;
  right: 15px;
  width: 10px;
  height: 10px;
  margin: 0;
  -webkit-transform: translateY(-50%) rotate(0deg);
  -ms-transform: translateY(-50%) rotate(0deg);
  transform: translateY(-50%) rotate(0deg);
  -webkit-transition: -webkit-transform 0.2s ease-in-out;
  transition: -webkit-transform 0.2s ease-in-out;
  transition: transform 0.2s ease-in-out;
  transition: transform 0.2s ease-in-out, -webkit-transform 0.2s ease-in-out;
  fill: currentColor;
}

.form-btn svg,
button.form-btn svg {
  width: 13px;
  height: 13px;
  margin-top: -3px;
  margin-right: 2px;
  fill: currentColor;
  vertical-align: middle;
}


/* DropDown */

.btn-dropdown .btn-dropdown-options {
  right: 0;
}

.btn-dropdown div.btn-dropdown-options {
  z-index: 2;
}

.btn-dropdown-options {
  font-family: "Haas Grot Text R Web", "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 14px;
  font-weight: 400;
  line-height: 20px;
  position: absolute;
  z-index: 1;
  top: calc(100%   8px);
  left: 0;
  min-width: 180px;
  margin-top: 4px;
  overflow: auto;
  border: 1px solid rgba(0, 0, 0, 0.05);
  border-radius: 8px;
  background: #fff;
  visibility: hidden;
  opacity: 0;
  transition: opacity 2s, visibility 2s;
  box-shadow: 0px 1px 2px rgba(128, 138, 157, 0.12), 0px 8px 32px rgba(128, 138, 157, 0.24);
}

.btn-dropdown-options ul {
  padding: 8px 0;
  list-style: none;
}

.btn-dropdown-options li.active a {
  color: #ea4c89;
  font-weight: 500;
  text-decoration: none;
}

.btn-dropdown-options a {
  display: block;
  padding: 8px 15px;
  color: #6e6d7a;
  font-size: 13px;
  text-decoration: none;
}



.btn-dropdown-options.dropdownShow {
  /* animation: 0.3s ease 0s 1 normal forwards running dropdownAnimation !important; */
  visibility: visible;
  opacity: 1;
}

.visuallyhidden {
  opacity: 0;
}

<span >
  <button id="showdropdown"  data-dropdown-state="closed">
    <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" role="img" >
      <path d="M21.5265 8.77171C22.1578 8.13764 22.1578 7.10962 21.5265 6.47555C20.8951 5.84148 19.8714 5.84148 19.24 6.47555L11.9999 13.7465L4.75996 6.47573C4.12858 5.84166 3.10492 5.84166 2.47354 6.47573C1.84215 7.10979 1.84215 8.13782 2.47354 8.77188L10.8332 17.1671C10.8408 17.1751 10.8486 17.183 10.8565 17.1909C11.0636 17.399 11.313 17.5388 11.577 17.6103C11.5834 17.6121 11.5899 17.6138 11.5964 17.6154C12.132 17.7536 12.7242 17.6122 13.1435 17.1911C13.1539 17.1807 13.1641 17.1702 13.1742 17.1596L21.5265 8.77171Z"></path>
    </svg>
    <span data-prompt="Variant" data-fade-default="true" >
      Sandle Brown
    </span>
</button>

<div id="variantMenu" >
  <ul>
    <li ><a href="?timeframe=">Now</a></li>
    <li ><a href="?timeframe=">Now</a></li>
    <li ><a href="?timeframe=">Now</a></li>
    <li ><a href="?timeframe=">Now</a></li>
    <li ><a href="?timeframe=">Now</a></li>
    <li ><a href="?timeframe=">Now</a></li>
  </ul>
</div>
</span>