Number.prototype.toCurrency = function(c, d, t){
var n = this,
    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) : "");
 };

 String.prototype.currencyToNumber = function(){
  return parseFloat(this.replace(/\./g, "").replace(/,/g, "."));
 }