How to reverse an animation on mouse out after hover

So, it is possible to have reverse animation on mouse out such as:

.class{
   transform: rotate(0deg);

}
.class:hover{
   transform: rotate(360deg);
}

but, when using @keyframes animation, I couldn't get it to work, e.g:

.class{
   animation-name: out;
   animation-duration:2s;

}
.class:hover{
   animation-name: in;
   animation-duration:5s;
   animation-iteration-count:infinite;

}
@keyframe in{
    to {transform: rotate(360deg);}
}

@keyframe out{
    to {transform: rotate(0deg);}
}

What is the optimal solution, knowing that I'd need iterations and animation itself?

http://jsfiddle.net/khalednabil/eWzBm/

I think that if you have a to, you must use a from. I would think of something like :

@keyframe in {
    from: transform: rotate(0deg);
    to: transform: rotate(360deg);
}

@keyframe out {
    from: transform: rotate(360deg);
    to: transform: rotate(0deg);
}

Of course must have checked it already, but I found strange that you only use the transform property since CSS3 is not fully implemented everywhere. Maybe it would work better with the following considerations :

• Chrome uses @-webkit-keyframes, no particuliar version needed
• Safari uses @-webkit-keyframes since version 5+
• Firefox uses @keyframes since version 16 (v5-15 used @-moz-keyframes)
• Opera uses @-webkit-keyframes version 15-22 (only v12 used @-o-keyframes)
• Internet Explorer uses @keyframes since version 10+

EDIT :

I came up with that fiddle :

http://jsfiddle.net/JjHNG/35/

Using minimal code. Is it approaching what you were expecting ?

Its much easier than all this: Simply transition the same property on your element

.earth { width:  0.92%;    transition: width 1s;  }
.earth:hover { width: 50%; transition: width 1s;  }

https://codepen.io/lafland/pen/MoEaoG

I don't think this is achievable using only CSS animations. I am assuming that CSS transitions do not fulfil your use case, because (for example) you want to chain two animations together, use multiple stops, iterations, or in some other way exploit the additional power animations grant you.

I've not found any way to trigger a CSS animation specifically on mouse-out without using JavaScript to attach "over" and "out" classes. Although you can use the base CSS declaration trigger an animation when the :hover ends, that same animation will then run on page load. Using "over" and "out" classes you can split the definition into the base (load) declaration and the two animation-trigger declarations.

The CSS for this solution would be:

.class {
    /* base element declaration */
}
.class.out {
   animation-name: out;
   animation-duration:2s;

}
.class.over {
   animation-name: in;
   animation-duration:5s;
   animation-iteration-count:infinite;
}
@keyframes in {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}
@keyframes out {
    from {
        transform: rotate(360deg);
    }
    to {
        transform: rotate(0deg);
    }
}

And using JavaScript (jQuery syntax) to bind the classes to the events:

$(".class").hover(
    function () {
        $(this).removeClass('out').addClass('over');
    },
    function () {
        $(this).removeClass('over').addClass('out');
    }
);

Creating a reversed animation is kind of overkill to a simple problem. What you need is:

animation-direction: reverse

However, this won't work on its own because animation spec forgot to add a way to restart the animation, so here is how you do it with the help of JS

let item = document.querySelector('.item')

// play normal
item.addEventListener('mouseover', () => {
  item.classList.add('active')
})

// play in reverse
item.addEventListener('mouseout', () => {
  item.style.opacity = 0 // avoid showing the init style while switching the 'active' class

  item.classList.add('in-active')
  item.classList.remove('active')

  // force dom update
  setTimeout(() => {
    item.classList.add('active')
    item.style.opacity = ''
  }, 5)

  item.addEventListener('animationend', onanimationend)
})

function onanimationend() {
  item.classList.remove('active', 'in-active')
  item.removeEventListener('animationend', onanimationend)
}

@keyframes spin {
  0% {
    transform: rotateY(0deg);
  }
  100% {
    transform: rotateY(180deg);
  }
}

div {
  background: black;
  padding: 1rem;
  display: inline-block;
}

.item {
  /* because span cant be animated */
  display: block;
  color: yellow;
  font-size: 2rem;
}

.item.active {
  animation: spin 1s forwards;
  animation-timing-function: ease-in-out;
}

.item.in-active {
  animation-direction: reverse;
}

<div>
  <span class="item">ABC</span>
</div>

we can use requestAnimationFrame to reset animation and reverse it when browser paints in next frame.

Also use onmouseenter and onmouseout event handlers to reverse animation direction

As per > Any rAFs queued in your event handlers will be executed in the ​same > frame​. Any rAFs queued in a rAF will be executed in the next frame​.

function fn(el, isEnter) {
  el.className = "";
   requestAnimationFrame(() => {
    requestAnimationFrame(() => {
        el.className = isEnter? "in": "out";
    });
  });  
}

.in{
  animation: k 1s forwards;
}

.out{
  animation: k 1s forwards;
  animation-direction: reverse;
}

@keyframes k
{
from {transform: rotate(0deg);}
to   {transform: rotate(360deg);}
}

<div style="width:100px; height:100px; background-color:red" 
  onmouseenter="fn(this, true)"
   onmouseleave="fn(this, false)"  
     ></div>

Would you be better off having just the one animation, but having it reverse?

animation-direction: reverse

Using transform in combination with transition works flawlessly for me:

.ani-grow {
    -webkit-transition: all 0.5s ease; 
    -moz-transition: all 0.5s ease; 
    -o-transition: all 0.5s ease; 
    -ms-transition: all 0.5s ease; 
    transition: all 0.5s ease; 
}
.ani-grow:hover {
    transform: scale(1.01);
}

Try this:

@keyframe in {
from {
    transform: rotate(0deg);
  }
  to {
    transform: rotate(360deg);
  }
}
@keyframe out {
from {
    transform: rotate(360deg);
  }
  to {
    transform: rotate(0deg);
  }
}

supported in Firefox 5+, IE 10+, Chrome, Safari 4+, Opera 12+

I've put together a CodePen with a CSS-only fix and one with 2 lines of jQuery to fix the on-page load issue. Continue reading to understand the 2 solutions in a simpler version.

https://codepen.io/MateoStabio/pen/jOVvwrM

If you are searching how to do this with CSS only, Xaltar's answer is simple, straightforward, and is the correct solution. The only downside is that the animation for the mouse out will play when the page loads. This happens because to make this work, you style your element with the OUT animation and the :hover with the IN animation.

svg path{
	animation: animateLogoOut 1s;
}
svg:hover path{
	animation: animateLogoIn 1s;
}

@keyframes animateLogoIn {
	from {stroke-dashoffset: -510px;}
    to {stroke-dashoffset: 0px;}
}
@keyframes animateLogoOut {
	from {stroke-dashoffset: 0px;}
    to {stroke-dashoffset: -510px;}
}

Some people found this solution to be useless as it played on page load. For me, this was the perfect solution. But I made a Codepen with both solutions as I will probably need them in the near future.

If you do not want the CSS animation on page load, you will need to use a tiny little script of JS that styles the element with the OUT animation only after the element has been hovered for the first time. We will do this by adding a class of .wasHovered to the element and style the added class with the OUT Animation.

jQuery:

$("svg").mouseout(function() {
	$(this).addClass("wasHovered");
 });

CSS:

svg path{

}

svg.wasHovered path{
	animation: animateLogoOut 1s;
}

svg:hover path{
    animation: animateLogoIn 1s;
}

@keyframes animateLogoIn {
    from {stroke-dashoffset: -510px;}
    to {stroke-dashoffset: 0px;}
}
@keyframes animateLogoOut {
    from {stroke-dashoffset: 0px;}
    to {stroke-dashoffset: -510px;}
}

And voila! You can find all of this and more on my codepen showing in detail the 2 options with an SVG logo hover animation.

https://codepen.io/MateoStabio/pen/jOVvwrM

Have tried several solutions here, nothing worked flawlessly; then Searched the web a bit more, to find GSAP at https://greensock.com/ (subject to license, but it's pretty permissive); once you reference the lib ...

 <script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/3.2.4/gsap.min.js"></script>

... you can go:

  var el = document.getElementById('divID');    
      
  // create a timeline for this element in paused state
  var tl = new TimelineMax({paused: true});

  // create your tween of the timeline in a variable
  tl
  .set(el,{willChange:"transform"})
  .to(el, 1, {transform:"rotate(60deg)", ease:Power1.easeInOut});

  // store the tween timeline in the javascript DOM node
  el.animation = tl;

  //create the event handler
  $(el).on("mouseenter",function(){
    //this.style.willChange = 'transform';
    this.animation.play();
  }).on("mouseleave",function(){
     //this.style.willChange = 'auto';
    this.animation.reverse();
  });

And it will work flawlessly.