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487Basic Numeric Enum Syntax
488Custom Numeric Enum Values
489Reverse Mapping in Numeric Enums
490Basic String Enum Syntax
491String Enums Have No Reverse Mapping
492Heterogeneous Enums (Mixed Types)
493Computed Enum Members
494Enums as Types
495Accessing Enum Members at Runtime
496Iterating Over Enum Members
497Enum Member Name vs Value
498When to Choose Numeric vs String Enums
499What const enums Are
500Declaring a const enum
501How const enums Are Inlined
502Performance Benefits of const enums
503Limitations of const enums
504const enums and isolatedModules
505preserveConstEnums Flag
506When to Use const enums
507Enums Generate Runtime Code
508Reverse Mappings Create Confusion
509Namespace Pollution
510String Enums Lack Reverse Mapping
511No Tree-Shaking for Enums
512Enums Don't Interop Well
513The const Enum Escape Hatch Trade-offs
514Enums and exactOptionalPropertyTypes
515Community Preference for Unions
516When Enums Still Make Sense
517String-Literal Unions as Enum Alternatives
518Type Safety: Enums vs Unions
519Runtime Behavior Differences
520Refactoring Safety and Autocomplete
521Iteration and Reflection Trade-offs
522Bundle Size and Tree-Shaking
523Library Authorship Considerations
524Choosing Between Enums and Unions

487Basic Numeric Enum Syntax
488Custom Numeric Enum Values
489Reverse Mapping in Numeric Enums
490Basic String Enum Syntax
491String Enums Have No Reverse Mapping
492Heterogeneous Enums (Mixed Types)
493Computed Enum Members
494Enums as Types
495Accessing Enum Members at Runtime
496Iterating Over Enum Members
497Enum Member Name vs Value
498When to Choose Numeric vs String Enums
499What const enums Are
500Declaring a const enum
501How const enums Are Inlined
502Performance Benefits of const enums
503Limitations of const enums
504const enums and isolatedModules
505preserveConstEnums Flag
506When to Use const enums
507Enums Generate Runtime Code
508Reverse Mappings Create Confusion
509Namespace Pollution
510String Enums Lack Reverse Mapping
511No Tree-Shaking for Enums
512Enums Don't Interop Well
513The const Enum Escape Hatch Trade-offs
514Enums and exactOptionalPropertyTypes
515Community Preference for Unions
516When Enums Still Make Sense
517String-Literal Unions as Enum Alternatives
518Type Safety: Enums vs Unions
519Runtime Behavior Differences
520Refactoring Safety and Autocomplete
521Iteration and Reflection Trade-offs
522Bundle Size and Tree-Shaking
523Library Authorship Considerations
524Choosing Between Enums and Unions

Lesson 519 of 1,796·12. EnumsPro lesson

Runtime Behavior Differences

Understanding that unions have zero runtime footprint while enums generate JavaScript objects.

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