JavaScript date and time formatting function sharing_javascript skills

Date.prototype.format = function(format){
var o = {
"M " : this.getMonth() 1, //month
"d " : this.getDate(), // day
"h " : this.getHours(), //hour
"m " : this.getMinutes(), //minute
"s " : this.getSeconds(), //second
"q " : Math.floor((this.getMonth() 3)/3), //quarter
"S" : this.getMilliseconds() //millisecond
}
if(/ (y )/.test(format)) format=format.replace(RegExp.$1,
(this.getFullYear() "").substr(4 - RegExp.$1.length));
for( var k in o)if(new RegExp("(" k ")").test(format))
format = format.replace(RegExp.$1,
RegExp.$1.length==1? o [k] :
("00" o[k]).substr(("" o[k]).length));
return format;
}