gistfile1.js

(function () {
  var r = /{(\w+)}/g;

  window._ = function (s, d) {
    if(!s)
      return "";
    if(!d)
      return s;

    return s.replace(r, function (c, p) {
      return d[p] || "";
    });
  };
})();

/*
Usage:

_("This is my {0} very long {1}", ["long", "string"]);
_("This is my {desc} very long {what}", {desc:"long", what:"string"});
*/