var parameterize = require('json-parameterization');

var input = {
  "{{key-prefix}}Key":  "{{now}} ms",
  "say":                "{{Hello World | to-lower }}"
};

var params = {
  'key-prefix':   'time',
  'now':          function() {
                    return new Date().getTime();
                  },
  'to-lower':     function(param) {
                    return param.toLowerCase();
                  }
};

parameterize(input, params);

{
  timeKey:      "1411165317832 ms",
  say:          "hello world"
}