Piscando
<b id='piscando' style="transition-duration:0.5s"> PISCANDO </b><script> var teste = 0; setInterval(piscar, 500); function piscar(){ if(teste<1){ teste++; document.getElementById('piscando').style.opacity = '1'; } else{ teste = 0; document.getElementById('piscando').style.opacity = '0'; }}; </script>