or css (shamelessly stolen from
http://www.jwz.org/jwz.css):
@keyframes blink { 0% { opacity:1; } 75% { opacity:1; } 76% { opacity:0; } 100% { opacity:0; }}
@-webkit-keyframes blink { 0% { opacity:1; } 75% { opacity:1; } 76% { opacity:0; } 100% { opacity:0; }}
@-moz-keyframes blink { 0% { opacity:1; } 75% { opacity:1; } 76% { opacity:0; } 100% { opacity:0; }}
@-ms-keyframes blink { 0% { opacity:1; } 75% { opacity:1; } 76% { opacity:0; } 100% { opacity:0; }}
@-o-keyframes blink { 0% { opacity:1; } 75% { opacity:1; } 76% { opacity:0; } 100% { opacity:0; }}
blink {
text-decoration: inherit;
animation: blink 0.75s ease-in infinite alternate;
-webkit-animation: blink 0.75s ease-in infinite alternate;
-moz-animation: blink 0.75s ease-in infinite alternate;
-ms-animation: blink 0.75s ease-in infinite alternate;
-o-animation: blink 0.75s ease-in infinite alternate;
}