017 - Reflection model

function createReflectionModel(source) {
  if (typeof source === typeof {}) {
      const target = Array.isArray(source)
          ? []
          : {};
      let i = -1;
      Object.keys(source).forEach((key) => {
           target[key] =
             createReflectionModel(source[key])
      });

      return target;
  }
  else {
    return void 0;
  }
}

createReflectionModel({a: 2, b: 3, c: {d: 4}});

// Ouput
// {a: undefined, b: undefined, c: {d: undefined}}