Q what is the difference between an interface and an abstract class

React Native. Python Design Patterns. Python Pillow. Python Turtle. Verbal Ability. Interview Questions. Company Questions. Artificial Intelligence. Cloud Computing. Data Science. Angular 7. Machine Learning. Data Structures. Operating System. Notice that the way you have to implement an interface is free. You can do that by instantiating a class, or with a simple object:. An interface doesn't exist at all at runtime, so it is not possible to make an introspection.

It is the classic JavaScript way to deal with object programming, but with a good control at compile time of the defined contracts. A class is both a contract and the implementation of a factory. An abstract class is also an implementation but incomplete. Especially, an abstract class exists at runtime, even if it has only abstract methods then instanceof can be used.

When you define an abstract class, you often try to control how a process has to be implemented. For example, you could write something like this:. This abstract class HouseRestorer defines how the methods layWires and layPipes will be used, but it is up to a child class to implement the specialized treatments before it can be used. Both approaches allow the same things to be done. But they are two different ways of solving a problem. A bigger difference in TypeScript is that abstract classes are available at runtime, while interfaces are compile time only.

This means that you cannot, for example, use instanceof with interfaces. If you don't really need runtime types, like the above example, or want to have implementations in the concrete classes only, go for interfaces. As they are compile time only, the size of the generated JS will be smaller. You are correct, but a second difference is that abstract classes can have method implementations.

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. What is the difference between interface and abstract class in Typescript?

SAP Expand child menu Expand. Web Expand child menu Expand. Must Learn Expand child menu Expand. Big Data Expand child menu Expand. Live Project Expand child menu Expand. AI Expand child menu Expand. Toggle Menu Close. Search for: Search. While adding new stuff to the interface, it is a nightmare to find all the implementors and implement newly defined stuff.

The interface does not have access modifiers.