mixin-pattern

Define the reusable behavior as a plain object, then call Object.assign with the class prototype as the target and the mixin object as the source. Every new instance of the class then has access to the mixin's properties through the prototype chain.

A mixin is an object used to add reusable functionality to other objects or classes without inheritance. Mixins cannot be used on their own; their sole purpose is to extend the behavior of a target, typically via Object.assign on a class prototype.

No. The React team discourages mixins because they add complexity and hurt maintainability. Use Hooks instead, or higher-order components where hooks do not fit; both achieve behavior sharing with better traceability.

Mixins modify shared prototypes, which can cause prototype pollution and naming collisions when multiple mixins define the same property. They also obscure where functionality originates, making code harder to trace and maintain.

Yes. You can use Object.assign to copy one mixin's properties onto another mixin, and methods can call super to reach the source behavior. The composed mixin is then assigned to the class prototype as usual.