The official TypeScript decorator proposal defines a class decorator as follows:
A class decorator function is a function that accepts a constructor function as its argument, and returns either undefined, the provided constructor function, or a new constructor function. Returning undefined is equivalent to returning the provided constructor function. – Ron Buckton, Decorators Proposal - TypeScript
A class decorator is used to modify the constructor of a class in some way. If the class decorator returns undefined, the original constructor remains the same. If the decorator ...
