timeout and interval

I. CSS3 animation shorthand (w3/spec)

@keyframes once { /* something */ }
@keyframes repeat { /* something */ }

#thing { animation:once 3s }
.things { animation:repeat 3s 300ms infinite }

II. js

setTimeout(function once(){ /* something */ }, 3e3);
// no direct way to specify an initial delay
setInterval(function repeat(){ /* something */ }, 3e3);

III. Hypothetical jQuery plugin (jQuery/docs)

$('#thing').timeout(function once(){ /* something */ }, 3e3);
$('.things').interval(function repeat(){ /* something */ }, 3e3, 300);