Kata: Fractions in JavaScript ES5 using the Function as Object pattern

One of the katas I use to start practicing TDD with my mentees is the Fractions kata. This kata is great to practice writing a good list of examples and doing small baby steps. I first learn about it while doing the J. B. Rainsberger wonderful TDD course.

We usually do it in Java, but last week Antonio and I did it in JavaScript ES5 using the Function as Object pattern. This is a very interesting pattern to create objects that you can use in any language with first-class functions and closures. In Codesai we use and teach this pattern when working in projects using ES5.

We had a great time doing this kata in several short sessions that are also helping me in my recovery process.

These are the tests we wrote:

and this is the resulting code:

See all the commits here if you want to follow the process. You can find all the code on this GitHub repo.