function format(s, formatter) {
  var v = parseFloat(s).formatMoney();
  if (formatter) v = formatter(v);
  return '£' + v;
}

//+ Jonas Raoni Soares Silva
//@ http://jsfromhell.com/number/fmt-money [rev. #2]

Number.prototype.formatMoney = 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) : "");
};