gistfile1.txt

var genKeyBuilder = function(key) {
  return function (data) {
    return key.replace(/(:(\w+))/g, function (_, _, inner) {
      return data[inner]
    })
  }
}

console.log(genKeyBuilder('/:controller/:action/:id')({controller: 'foo', action: 'bar', id: '123'}))
// #=> /foo/bar/123