How to play a animation with js after glam ready?

[yeso]

.play{ animation-duration:.8s; animation-name:jump; animation-iteration-count:infinite; animation-timing-function:ease-in-out; } @keyframes jump { 0% { transform:translateY(0); } 50% { transform:translateY(0.3); } 100%{ transform:translateY(0); } }

obj.addEventListener('viewover', function(e) { e.target.className = 'play'; });

/////////////////// it do not work~