Doc-holiday introduces an extension to normal JSDoc convention with the introduction of constraints.
A constraint is a limitation on the value (a parameter or return value) may have in order to fit the specification.
For example, suppose you have a parameter named “age” which is meant to represent the age of a user. You have specified that this should be a type “number”, and the expectation is that callers of this function will pass reasonable user ages, such as 16, 30, 44, 61, or 72. But what if someone passes 15.59? Or -12? Or 1,234?
As a good programmer, you have code in this function dedicated to parameter validation that would otherwise break your algorithm, and you reject or clamp such values accordingly (or you missed a case, and your app crashes).
But does the documentation reflect that?
Maybe you spelled all of this out in the function or parameter descriptions, but probably not, because that’s tedious to do and even if you did it would not stand out as anything to take note of because the comment would be a long rambling block of text.
This is where constraints come in.
Constraints allow you to declare the runtime limitations of a value in a concise format in your comments. This is expanded upon in the final documentation to render as a separately styled list of restrictions upon the value that is easy to note by those reading the documentation.
Learn about constraints and how to use them here
If you are looking for a corresponding validation library you can use at runtime to enforce this in your code, we have that too! the validate function can be imported into your sources and used to check that a value passed at runtime meets the specification documented.