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457What Are Literal Types?
458String Literal Types Syntax
459Numeric Literal Types Syntax
460Boolean as Literal Types
461Literal Types in Function Parameters
462Literal Types in Return Values
463Widening from Literals to Primitives
464Preventing Widening with Type Annotations
465Combining Literal Types with Unions
466When to Use Literal Types
467The Widening Problem Without as const
468Basic as const Syntax
469as const on Primitive Values
470as const on Arrays
471as const on Objects
472Nested as const Inference
473as const vs readonly Modifiers
474as const for Configuration Objects
475Extracting Types from as const Values
476as const for Enum-Like Patterns
477When Not to Use as const
478as const in Function Returns
479String Literal Unions as Lightweight Enums
480Type-Safe Switches with Literal Unions
481Literal Unions vs Enums: Trade-offs
482Extracting Union Members as Values
483Autocompletion Benefits of Literal Unions
484Combining Literal Unions for Complex States
485Mapping Over Literal Unions
486When to Graduate to Real Enums

457What Are Literal Types?
458String Literal Types Syntax
459Numeric Literal Types Syntax
460Boolean as Literal Types
461Literal Types in Function Parameters
462Literal Types in Return Values
463Widening from Literals to Primitives
464Preventing Widening with Type Annotations
465Combining Literal Types with Unions
466When to Use Literal Types
467The Widening Problem Without as const
468Basic as const Syntax
469as const on Primitive Values
470as const on Arrays
471as const on Objects
472Nested as const Inference
473as const vs readonly Modifiers
474as const for Configuration Objects
475Extracting Types from as const Values
476as const for Enum-Like Patterns
477When Not to Use as const
478as const in Function Returns
479String Literal Unions as Lightweight Enums
480Type-Safe Switches with Literal Unions
481Literal Unions vs Enums: Trade-offs
482Extracting Union Members as Values
483Autocompletion Benefits of Literal Unions
484Combining Literal Unions for Complex States
485Mapping Over Literal Unions
486When to Graduate to Real Enums

Lesson 461 of 1,796·11. Literal TypesPro lesson

Literal Types in Function Parameters

Use literal types to restrict function arguments to specific allowed string or number values.

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