////////
css
.anim{
animation:move 1s ease forwards infinit;
}
@keyframes move {
0%{starting state}
100%{ending state}
}
///////
const btn=document.queryselector("button");
const animatedElm =document.queryselector(".elm");
btn.addEventListener("click",eventhandler);
animatedElm.classList.toggle("anim");
function eventhandler(){
}