SOLID Principles

The SOLID principles are five design rules—Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, and Dependency Inversion—that guide object-oriented programming to improve code maintainability, extensibility, and understandability.

To implement the Single Responsibility Principle in TypeScript, you ensure classes have only one reason to change by separating concerns. This Skill provides TypeScript code examples demonstrating how to refactor complex classes into focused, maintainable components.

You use the Open/Closed Principle to design extensible software by allowing classes to be extended without modifying their existing source code. This Skill provides guidance on applying this rule to design new features that can be easily extended in TypeScript.

No, you do not need TypeScript to apply these software design principles, as SOLID concepts are platform-agnostic. However, this Skill specifically provides its code examples and implementation guidance using TypeScript to demonstrate object-oriented programming techniques.

You should refactor code using the Dependency Inversion Principle when you want to encourage abstraction over concretion in your object-oriented programming. This Skill helps you decouple high-level modules from low-level modules to improve code maintainability.

The best way to ensure subtype substitutability in an inheritance hierarchy is applying the Liskov Substitution Principle. This Skill provides guidance and TypeScript examples to guarantee that subtypes can replace base types without altering code correctness.