Essential TypeScript 5, Third Edition

12 Using generic types

This chapter covers

• Using generic type parameters as type placeholders
• Instantiating classes with generic type arguments
• Constraining generic type parameters
• Guarding generic types with predicate functions
• Defining interfaces with generic type parameters

Generic types are placeholders for types that are resolved when a class or function is used, allowing type-safe code to be written that can deal with a range of different types, such as collection classes. This is a concept that is more easily demonstrated than explained, so I start this chapter with an example of the problem that generic types solve and then describe the basic ways that generic types are used. In chapter 13, I describe the advanced generic type features ...