$ npm install el-transition

$ yarn add el-transition

The purpose of this package is to handle enter/leave transition using classes or data attributes. This is similar to the implementations you find in vue.js and alpine.js.

Both class based and dataset attributes are supported.

To hide and show elements an implemenation of the class hidden is required.

.hidden {
  display: none
}

el-transition exports three async functions enter, leave, and toggle. Each function expects an HTML DOM element as the first argument and optional transition name as the second.

// app.js
import {enter, leave, toggle} from 'el-transition'

function open() {
    enter(element).then(() => {
        console.log("Enter transition complete")
    })
}

// remove element when close
function close() {
    leave(element).then(() => {
        element.destroy();
    })
}

// calls enter or leave based on presence of the class hidden
function toggle() {
    toggle(element);
}

When using dataset attributes el-transtion expects the following.

• data-transition-enter: Applied during the entire entering phase.
• data-transition-enter-start: Added before element is inserted, removed one frame after element is inserted.
• data-transition-enter-end: Added one frame after element is inserted (at the same time enter-start is removed), removed when transition/animation finishes.
• data-transition-leave: Applied during the entire leaving phase.
• data-transition-leave-start: Added immediately when a leaving transition is triggered, removed after one frame.
• data-transition-leave-end: Added one frame after a leaving transition is triggered (at the same time leave-start is removed), removed when the transition/animation finishes.

<!-- dropdown.html -->
<div class="relative inline-block text-left">
  <div>
    <span class="rounded-md shadow-sm">
      <button type="button" class="dropdown-button" id="dropdown-btn">
        Options
      </button>
    </span>
  </div>

    <!-- declare enter leave anmiations using data attributes -->
    <div id="dropdown-menu" class="menu hidden"
        data-transition-enter="transition ease-out duration-100"
        data-transition-enter-start="transform opacity-0 scale-95"
        data-transition-enter-end="transform opacity-100 scale-100"
        data-transition-leave="transition ease-in duration-75"
        data-transition-leave-start="transform opacity-100 scale-100"
        data-transition-leave-end="transform opacity-0 scale-95"
    >
    <div class="rounded-md bg-white shadow-xs">
      <div class="py-1" role="menu" aria-orientation="vertical" aria-labelledby="options-menu">
        <!-- Menu links -->
      </div>
    </div>
  </div>
</div>

import {enter, leave, toggle} from 'el-transition'

const dropdownMenu = document.getElementById("dropdown-menu")
const dropdownBtn = document.getElementById("dropdown-btn")

function openMenu() {
  enter(dropdownMenu)
}

function closeMenu() {
  leave(dropdownMenu)
}

function toggleDropdownMenu() {
    toggle(dropdownMenu)
}

dropdownBtn.addEventListener('click', toggleDropdownMenu)

You may specificy a transition name and el-transtion will handle applying the inferred css classses at the each stage. If data attributes are set, those will take precedence.

Using the example transition name dropdown we need can declare a class per stage.

• .dropdown-enter: Applied during the entire entering phase.
• .dropdown-enter-start: Added before element is inserted, removed one frame after element is inserted.
• .dropdown-enter-end: Added one frame after element is inserted (at the same time enter-start is removed), removed when transition/animation finishes.
• .dropdown-leave: Applied during the entire leaving phase.
• .dropdown-leave-start: Added immediately when a leaving transition is triggered, removed after one frame.
• .dropdown-leave-end: Added one frame after a leaving transition is triggered (at the same time leave-start is removed), removed when the transition/animation finishes.

// application.scss

.dropdown-enter {
  @apply transition ease-out duration-100;
}

.dropdown-enter-start {
  @apply transform opacity-0 scale-95;
}
 .dropdown-enter-end {
  @apply transform opacity-100 scale-100;
 }

.dropdown-leave {
   @apply transition ease-in duration-75;
 }

.dropdown-leave-start {
  @apply transform opacity-100 scale-100;
}

.dropdown-leave-end {
  @apply transform opacity-0 scale-95;
}

<!-- dropdown.html -->
<div class="relative inline-block text-left">
  <div>
    <span class="rounded-md shadow-sm">
      <button type="button" class="dropdown-button" id="dropdown-btn">
        Options
      </button>
    </span>
  </div>

  <div id="dropdown-menu" class="menu hidden">
    <div class="rounded-md bg-white shadow-xs">
      <div class="py-1" role="menu" aria-orientation="vertical" aria-labelledby="options-menu">
        <!-- Menu links -->
      </div>
    </div>
  </div>
</div>

// app.js
import {enter, leave, toggle} from 'el-transition'

const dropdownMenu = document.getElementById("dropdown-menu")
const dropdownBtn = document.getElementById("dropdown-btn")

function openMenu() {
  enter(dropdownMenu, 'dropdown')
}

function closeMenu() {
  leave(dropdownMenu, 'dropdown')
}

function toggleDropdownMenu() {
    toggle(dropdownMenu, 'dropdown')
}

dropdownBtn.addEventListener('click', toggleDropdownMenu)