Can you explain the open-closed principle in the context of SOLID?

The Open/Closed Principle from the SOLID set states that software entities (classes, modules, functions) should be open for extension but closed for modification. This means that the system's behavior can be extended without changing existing code.

For example, if you have a class implementing some logic and need to add new functionality, you should not modify the original class but create a new class that extends or inherits from it, adding the desired behavior. This reduces the risk of errors and simplifies maintenance.

In Node.js, this is often achieved through the use of abstractions, interfaces (via TypeScript or conventions), and design patterns such as strategy or decorator.