How to play an animation on hover and pause when hover is not active

Question

I have a button that I want to rotate when the mouse hovers over it. However, while the spinning works when the mouse enters, it also spins when the mouse leaves. Here is what I mean:

button {
  transition: transform 1.2s linear;
}

button:hover {
  transform: rotate(360deg);
}

<button>X</button>

Is there any way to just make the mouse spin when the mouse enters?

Answer 1

Use animation instead of transition and make use of animation-play-state^MDN

button{
  animation: rotate360 1.2s linear infinite;  /* animation set */
  animation-play-state: paused;               /* but paused */
}
button:hover{
  animation-play-state: running;              /* trigger on hover */
}
@keyframes rotate360 {
  to { transform: rotate(360deg); }           
}

<button>X</button>