Built-ins: ReturnType, Parameters, InstanceType, etc.
Know and apply key built-in utility types: ReturnType, Parameters, InstanceType, ThisParameterType, OmitThisParameter, ConstructorParameters.
Intro
Goal: Use built-in utility types efficiently. You'll map functions/constructors to their return, parameters, instance, and this types.
- ReturnType, Parameters
- InstanceType, ConstructorParameters
- ThisParameterType, OmitThisParameter
ReturnType & Parameters
ReturnType infers the return type, Parameters the parameter tuple; reduces fragility in refactors.
function greet(name: string) { return `Hi ${name}` }
// built-ins
type R = ReturnType<typeof greet> // string
type P = Parameters<typeof greet> // [name: string]All lessons in this course
- T extends U ? X : Y in practice
- infer for ReturnType-like utilities
- Built-ins: ReturnType, Parameters, InstanceType, etc.