loading... animation for buttons and such

sometimes I like to have a little loading animation using just the button label, so here is a snippet to generate the string - it does the little dots-increase that we all know from elsewhere.

var c=0,t,dots='Loading';
    function loadanim(){
    while(c<=12){         c++; c %4 == 0 ? dots='Loading ' : dots += '.';         document.getElementById('txt').value=dots;         t=setTimeout("loadanim()",300); return dots;     }     if(c>=13) {
        clearTimeout(t);
    }
}