Modern Front-End Development for Rails

Defining Interfaces

Sometimes the type checking only cares about a subset of the properties of an object, or you have a common set of properties that might be shared by a number of different objects that are otherwise unrelated. It’s useful to allow the type checking system to be as specific as possible and to specify that the objects being used are restricted to only the properties that are being used in a specific context.

Alternately, you might have some data in your system, such as the result of a server call that has returned JSON objects, and you’d like to assert in the type system that the certain properties must exist in the data. But you don’t necessarily need to declare a class because there might not be any behavior for that data, ...