Javascript Number money(c, d, t)

Number.prototype.money = function(c, d, t){
var n = this, /* ww w .  j  a  v  a  2s  .  co m*/
 c = isNaN(c = Math.abs(c)) ? 2 : c, 
 d = d == undefined ? "." : d, 
 t = t == undefined ? "," : t, 
 s = n < 0 ? "-" : "", 
 i = parseInt(n = Math.abs(+n || 0).toFixed(c)) + "", 
 j = (j = i.length) > 3 ? j % 3 : 0;
 return s + (j ? i.substr(0, j) + t : "") + i.substr(j).replace(/(\d{3})(?=\d)/g, "$1" + t) + (c ? d + Math.abs(n - i).toFixed(c).slice(2) : "");
 };