Apply a CSS class for each stage of a CSS transition.

Usage no npm install needed!

<script type="module">
  import 4rkCssTransition from 'https://cdn.skypack.dev/@4rk/css-transition';



Apply a CSS class for each stage of a CSS transition.

This is basically a react-free rip-off of react-transition-group.

It is super useful to make CSS transitions from display: none; to display: whatever;.


There is a simple usage demo which can be run as follows:

yarn start


The basic idea of this library is that in order to control a CSS transition using JavaScript, you have to think of it as a three-staged process:

  1. Start:
    • Set prerequisites for the animation, e.g. set display: block; and transition: all 0.3s ease;
  2. Active:
    • One requestAnimationFrame after start
    • Change transitioning properties, e.g. set opacity: 1;
  3. Done:
    • After transitionend or a timeout
    • Make transition changes permanent, this means usually setting the same properties as during active stage
    • During exit, this would be the place to set display back to none.

For a code example, please take a look at the demo.


  • Apply pointer-events: none; during .exit and .exit-active to prevent user interaction during transition
  • How to cope with the timeout warning:
    1. Make sure that a transition is happening on the element specified during instantiation, e.g. it is not a parent element but the direct element on which the transitions are happening. If not, create separate CSSTransition instances for each element.
    2. Make sure that there is actually a transition. The instance is waiting for the first transitionend event.
    3. Check whether your transition takes less time than the configured timeout which is by default 500ms. If not, increase the timeout.

Creating a release

Certain steps need to be done in order to create a new release:

  1. Decide on a semver version number
  2. Start a new release using git flow release start [version number]
  3. Update the package.json version
  4. Run yarn run release
  5. Commit changes: git commit -a -m "Prepare release [version number]"
  6. Finish release using git flow release finish
  7. Push all changes: git push origin --all && git push origin --tags