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663What Are Utility Types?
664The Partial<T> Utility
665Practical Partial: Update Functions
666Partial with Nested Objects
667The Required<T> Utility
668Required for Validation Results
669The Readonly<T> Utility
670Readonly vs const
671Readonly with Arrays and Tuples
672Combining Utility Types
673When to Use Each Utility
674Deep vs Shallow Transformations
675Pick<T, K>: Selecting a Subset of Properties
676Pick with String Literal Unions
677Pick Use Cases: API Response Subsets
678Omit<T, K>: Excluding Properties
679Omit vs Pick: Choosing the Right Tool
680Omit for Database Models Without Computed Fields
681Record<K, T>: Creating Uniform Object Types
682Record with String Literal Keys
683Record for Status Maps and Lookup Tables
684Combining Pick and Record
685Record vs Index Signatures
686Practical Patterns: Forms and Validation
687Understanding Exclude<T, U>
688Exclude with String Literal Unions
689Extract<T, U> Fundamentals
690Extract for Pattern Matching
691Exclude vs Extract Mental Model
692NonNullable<T> Basics
693NonNullable in Strictness Contexts
694Combining Exclude with Discriminated Unions
695Extract for Type-Safe Subsets
696Common Patterns with Exclude, Extract, and NonNullable
697ReturnType: Extract a Function's Return Type
698ReturnType with Generic Functions
699ReturnType for Async Functions
700Parameters: Extract Function Parameter Types
701Accessing Individual Parameters
702Parameters with Rest and Optional Args
703Combining ReturnType and Parameters
704ConstructorParameters: Extract Constructor Args
705ConstructorParameters with Abstract Classes
706Creating Factory Functions from Constructors
707When These Utilities Save Repetition
708Limitations and Edge Cases
709InstanceType<T> for Constructor Types
710Awaited<T> for Promise Unwrapping
711ThisParameterType<T> and OmitThisParameter<T>
712Uppercase, Lowercase, Capitalize, Uncapitalize String Utilities
713NoInfer<T> for Disabling Inference
714Combining Multiple Utilities
715When to Use vs Custom Mapped Types
716The Full Standard Library Reference

663What Are Utility Types?
664The Partial<T> Utility
665Practical Partial: Update Functions
666Partial with Nested Objects
667The Required<T> Utility
668Required for Validation Results
669The Readonly<T> Utility
670Readonly vs const
671Readonly with Arrays and Tuples
672Combining Utility Types
673When to Use Each Utility
674Deep vs Shallow Transformations
675Pick<T, K>: Selecting a Subset of Properties
676Pick with String Literal Unions
677Pick Use Cases: API Response Subsets
678Omit<T, K>: Excluding Properties
679Omit vs Pick: Choosing the Right Tool
680Omit for Database Models Without Computed Fields
681Record<K, T>: Creating Uniform Object Types
682Record with String Literal Keys
683Record for Status Maps and Lookup Tables
684Combining Pick and Record
685Record vs Index Signatures
686Practical Patterns: Forms and Validation
687Understanding Exclude<T, U>
688Exclude with String Literal Unions
689Extract<T, U> Fundamentals
690Extract for Pattern Matching
691Exclude vs Extract Mental Model
692NonNullable<T> Basics
693NonNullable in Strictness Contexts
694Combining Exclude with Discriminated Unions
695Extract for Type-Safe Subsets
696Common Patterns with Exclude, Extract, and NonNullable
697ReturnType: Extract a Function's Return Type
698ReturnType with Generic Functions
699ReturnType for Async Functions
700Parameters: Extract Function Parameter Types
701Accessing Individual Parameters
702Parameters with Rest and Optional Args
703Combining ReturnType and Parameters
704ConstructorParameters: Extract Constructor Args
705ConstructorParameters with Abstract Classes
706Creating Factory Functions from Constructors
707When These Utilities Save Repetition
708Limitations and Edge Cases
709InstanceType<T> for Constructor Types
710Awaited<T> for Promise Unwrapping
711ThisParameterType<T> and OmitThisParameter<T>
712Uppercase, Lowercase, Capitalize, Uncapitalize String Utilities
713NoInfer<T> for Disabling Inference
714Combining Multiple Utilities
715When to Use vs Custom Mapped Types
716The Full Standard Library Reference

Lesson 697 of 1,796·16. Utility TypesPro lesson

ReturnType: Extract a Function's Return Type

Use ReturnType<T> to derive the return type of any function type, enabling type reuse without duplication.

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