Interchangeable elements and ids
Elements and ids can be interchangeable in function calls, if a function expects a document id. It can normally take the element directly in place of the id.
Configuration via JSON
Options are typically passed to functions as JSON objects.
Loops are codes as higher-order functions
Loops are often replaced by Enumerations.
Higher-order combining forms are used
Prototype uses unusual combining forms, such as combining functions prior to their application.