[martinaparicio]

Once I had to work with a well written but undocumented NodeJS application (in ES5, dynamically typed). I didn't know what to expect from any function, neither the structure of the data. Suppose you have a function that returns an Employee, but you do not know how the Employee is defined, so you need to look on the database schema to know the basic structure -- but when you use it you see that there is data that wasn't in the initial definition! The Employee is mutable and some data was added in some place along the app. Good look finding the actual expected output! This is easily fixed by adding some comments about the expected data returned by the function.

Please, just document your code and update if any code comment if needed. It's cheap and easy.

[douche]

Yikes. That's one of the things I like least about dynamic languages. Being able to add properties onto an object after it is initially defined willynilly is a disaster for trying to understand what is going on.