String.prototype.supplant from Douglas Crockford's Remedial JavaScript

String.prototype.supplant.js

String.prototype.supplant = function(o) {
  return this.replace(/{([^{}]*)}/g,function(a, b) {
    var r = o[b];
    return typeof r === 'string' || typeof r === 'number' ? r : a;
  });
};