i made a navbar for practice and tried to hide and show its content only when its title is clicked. i managed to do it with toggling a hidden class on and off. but i also want it to have transition and slide down not just to apear out of nowhere. i couldn't do this part.

i put transition inside nav-bar__list-box tweaked the hidden class with and without display:block but i didn't have any success.

hidden class:

.u-hidden-navbar {
    display: none;
    visibility: hidden;
    height: 0 !important;
}

idk what else to do but to ask here for advise.

const btnNavBar = document.querySelectorAll(".nav-bar__heading-box");
const navList = document.querySelectorAll(".nav-bar__list-box");

for (let i = 0; i < btnNavBar.length; i  ) {
  btnNavBar[i].addEventListener(`click`, function () {
    navList[i].classList.toggle("u-hidden-navbar");
    for (let b = 0; b < navList.length; b  ) {
      if (b !== i) {
        navList[b].classList.add("u-hidden-navbar");
      }
    }
  });
}

*,
*::after,
*::before {
  box-sizing: inherit;
  padding: 0;
  margin: 0;
}

html {
  font-size: 62.5%;
}

body {
  box-sizing: border-box;
  font-size: 1.6rem;
  line-height: 1.5;
}

ul {
  list-style: none;
}

a {
  text-decoration: none;
  display: inline-block;
  color: #e6e6e6;
}

img {
  vertical-align: bottom;
}

.u-hidden-navbar {
  display: none;
  visibility: hidden;
  height: 0 !important;
}

.nav-bar {
  margin: 2rem;
  border-radius: 0.8rem;
  overflow: hidden;
  order: 1;
  background-color: #e6e6e6;
  width: 30rem;
}
.nav-bar__heading-box {
  background-color: #3b3b3b;
  padding: 1rem;
}
.nav-bar__heading-box:not(:last-child) {
  border-bottom: 1px solid #1b1b1b;
}
.nav-bar__list-box {
  font-weight: 700;
  font-size: 1.6rem;
  transition: 5s all ease;
}
.nav-bar__item:not(:last-child) {
  border-bottom: 1px solid #1b1b1b;
}
.nav-bar__link {
  padding: 1rem 2rem 1rem;
  color: #973ae4;
  position: relative;
  display: block;
  transition: 0.4s all ease;
}
.nav-bar__link:hover {
  color: #e6e6e6;
  transform: translateY(0);
}
.nav-bar__link:hover::before {
  transform: scaleX(1);
  box-shadow: inset 0.2rem 0.2rem 0.5rem rgba(27, 27, 27, 0.6);
  opacity: 1;
}
.nav-bar__link::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  height: 100%;
  width: 100%;
  transform-origin: left;
  transform: scaleX(0.1);
  opacity: 0;
  background-color: #973ae4;
  transition: all 0.3s ease-in-out;
  z-index: -1;
}

<aside >
        <div >
          <h3 >HTML Topics</h3>
        </div>
        <div >
          <ul >
            <li >
              <a
                href="pages/js_topic_01.html"
                
                target="content"
                >Link</a
              >
            </li>
            <li >
              <a
                href="pages/js_topic_01.html"
                
                target="content"
                >Link</a
              >
            </li>
          </ul>
        </div>
        <div >
          <h3 >CSS Topics</h3>
        </div>
        <div >
          <ul >
            <li >
              <a
                href="pages/js_topic_01.html"
                
                target="content"
                >Link</a
              >
            </li>
            <li >
              <a
                href="pages/js_topic_01.html"
                
                target="content"
                >Link</a
              >
            </li>
          </ul>
        </div>
        <div >
          <h3 >JS Topics</h3>
        </div>
        <div >
          <ul >
            <li >
              <a
                href="pages/js_topic_01.html"
                
                target="content"
                >1- JS High-level overview</a
              >
            </li>
            <li >
              <a href="hello.html"  target="content"
                >Link</a
              >
            </li>
          </ul>
        </div>
      </aside>

CodePudding user response：

The browser does not know how to interpolate this kind of animation, so you'll have to be a little bit more specific about how you'd like the hidden element to appear.

Switching from display: block to display: none or from visibility: visible to visibility: hidden is a "on/off" situation with no way to guess what the middle state will be...

Instead you could try to transition from :

• opacity: 0 to opacity: 1
• transform: scaleY(0) to transform: scaleY(1)
• both

You can be really creative, and rely on keyframed animations with several intermediate steps, but it's up to you to define the strategy.

document.querySelector('button').addEventListener('click', () => {
  document.querySelector('.togglable').classList.toggle('hidden')
})

.togglable{
  padding: 50px;
  background: red;
  transform: scaleY(1);
  opacity: 1;
  color: #FFF;
  transition: .75s;
}

.togglable.hidden{
  opacity: 0;
  transform: scaleY(0);
}

<button>Click me</button>

<div >Hello</div>

CodePudding user response：

Try using this library or one similar. https://animejs.com/