This detailed tutorial shows how to implement pure functions in JavaScript that are deterministic and referentially transparent, and create no side effects.

Keep following along as Thau gets down and dirty with the JavaScript Document Object Model, windows and frames, JavaScript syntax with loops, arrays, and functions, and forms.

Since this new object is a JavaScript array, Arquero methods won’t work on it anymore, but conventional array methods will. Here’s an example: 'The regions are ' + region_array. join (', ') ...

Even then, if you declare a const and assign it an object, you can change anything you want within the object itself. In functional programming, this is a big no-no. Mutations are considered a ...