JS format string

JavaScript

var format = function (str /*[values]*/) {
  var args = arguments;
  var s = str; 
  [].shift.apply(args);
  return s.replace(/\{(\d+)\}/g, function (m, n) { return args[n]; });
};

var s1 = 'Added {0} by {1} to your collection';
var s2 = 'Your balance is {0:N0} USD';

console.log("s1 = " + format(s1, "SMTH", "WHO"));
console.log("s2 = " + format(s2, 123));