<script language="javascript">
var sSrc='vstr=[1]oa.gif,[2]2.gif,[3]list.jpg';
function rep(s,i){
var sFnc='return arguments[0].replace(/\\[#\\][^\\.]*\\.[^\\,$]*[\\,$]*/gi,\'\');';
sFnc=sFnc.replace('#',i);
var of=new Function(sFnc);
return of(s);
}
alert(rep(sSrc,1));
alert(rep(sSrc,2));
alert(rep(sSrc,3));
</script>