CSS Transition after animation ends

问题

I have a css transition that moves an element on hover and an animation that rotates the element on hover too. There's a delay on the animation equal to the transition duration so that after it's transitioned to it's correct position, the animation starts. And it works nice, however, when we mouse off, the animation stops but it doesn't transition back down.

Is it possible to get it to transition back after we mouse off and the animation ends?

You can see an example here: http://codepen.io/jhealey5/pen/zvXBxM

Simplified code here:

    div {
        width: 200px;
        height: 200px;
        margin: 40px auto;
        background-color: #b00;
        position: relative;

        &:hover {
            span {
                transform: translateY(-60px);
                animation-name: rotate;
                animation-duration: 1s;
                animation-delay: .5s;
                animation-iteration-count: infinite;
                animation-direction: alternate;
            }
        }
    }

    span {
        position: absolute;
        width: 20px;
        height: 20px;
        background-color: #fff;
        bottom: 10px;
        left: 0;
        right: 0;
        margin: auto;
        transition: .5s;
    }

    @keyframes rotate {
        from {
            transform: translateY(-60px) rotate(0);
        }
        to {
            transform: translateY(-60px) rotate(-90deg);
        }
    }

回答1:

I have forked your project and adapted it so it works. You can find it here.

What I have changed is the following:

I give the white square a start position of top: 150px and let it, on hover of div, get a top: 0. The span gets a transition: top .5s and with that it goes to top: 0; on hover and back to top: 150px; when the mouse leaves.

I have removed the translateY(-60px); from the animation, because that would move it even more up when the animation would start.

Here's your new CSS:

div {
    width: 200px;
    height: 200px;
    margin: 40px auto;
    background-color: #b00;
    position: relative;

    &:hover {
        span {
            top: 0px;
            animation: rotate 1s infinite .5s alternate;
            animation-direction: alternate;
        }
    }
}

span {
    position: absolute;
    width: 20px;
    height: 20px;
    background-color: #fff;
    bottom: 10px;
    left: 0;
    right: 0;
    top: 150px;
    margin: auto;
    transition: top .5s;
}

@keyframes rotate {
    from {
        transform: rotate(0);
    }
    to {
        transform: rotate(-90deg);
    }
}

Edit: The problem is that an animation is time-based and not action-based, which means that as soon as you trigger an animation, a timer starts running and it will run through all the keyframes until the set time has passed. Hover-in and hover-out have no effect, except that the timer can be stopped prematurely, but the animation will not continue (or reversed, which you wanted) after that. transition is action-based, which means it gets triggered every time an action (for example :hover) is happening. On :hover, this means it takes .5s to go to top:0 and when the hover ends, it takes .5s to got to top:150px.

I hope the above addition makes sense :)

As you can see, I also cleaned up a bit in your animation-name: etc., since it can be combined into one line.

回答2:

As Harry pointed out, the problem is that you are animating/transitioning the same property, in this case transform. It looks like the current versions of Chrome/FF will allow the animation to take control of the property, thereby breaking the transition. It seems like the only way to work around this is to transition/animation a different property. Since you need to continue rotating the element, you could translate/position the element by changing the bottom property instead. I know that doesn't produce the exact same results, but nonetheless, it does move the element (just not relative to the parent element).

Updated Example

div:hover  span {
  bottom: 80px;
}

---

As an alternative, you could also wrap the span element, and then translate that element instead.

In the example below, the .wrapper element is transitioned to translateY(-60px) on hover, and then the child span element is rotated and maintains the animation.

Example Here

div {
  width: 200px;
  height: 200px;
  margin: 40px auto;
  background-color: #b00;
  position: relative;
}
div:hover .wrapper {
  transform: translateY(-60px);
}
div:hover .wrapper span {
  animation-name: rotate;
  animation-duration: 1s;
  animation-delay: .5s;
  animation-iteration-count: infinite;
  animation-direction: alternate;
}
.wrapper {
  display: inline-block;
  transition: .5s;
  position: absolute;
  bottom: 10px;
  left: 0;
  right: 0;
  text-align: center;
}
.wrapper span {
  display: inline-block;
  width: 20px;
  height: 20px;
  background-color: #fff;
}
@keyframes rotate {
  from {
    transform: rotate(0);
  }
  to {
    transform: rotate(-90deg);
  }
}

<div>
  <span class="wrapper">
	  <span></span>
  </span>
</div>

来源：https://stackoverflow.com/questions/33829469/css-transition-after-animation-ends