The folder structure of our enumeration app extends the structure of the validation app by adding the file Enumeration.js in the lib folder. Thus, we get the following folder structure with four files in the lib folder:

publicLibrary
  css
  lib
    browserShims.js
    errorTypes.js
    util.js
    Enumeration.js
  src
  index.html

In the Enumeration.js file, discussed in the next section, we define a meta-class Enumeration for creating enumerations as instances of this meta-class with the help of statements like GenderEL = new Enumeration(["male", "female", "undetermined"]).