How to read such syntax correctly?

Question

Programming

Where can I read the rules for composing and correctly reading such syntax?

Answer 1

In my opinion, this is a generally accepted syntax, I won’t tell you where to look, but optional arguments to functions are always indicated in square brackets.
There are other similar options:

arr.map(Function callback[, Object context = null])
//
функция(Тип имя[, Тип имя = значение_по_умолчанию])

Answer 2

Decent documentation should describe this syntax at the beginning. (If it was written by a person familiar with mathematics.)

Answer 3

what is not clear? there is an instance of the array class - arr, which has a sort method that accepts a sort method, chosen either from the available ones (read in the documentation), or from self-written

Answer 4

An optional argument to define the sort key, mostly relevant when sorting structures with multiple parameters. For example points on x or y .