13 — Mapped Types & Template Literal Types

Core Concepts

• Mapped types — transform every property in a type: { [K in keyof T]: ... }
• Key remapping — rename keys with as: { [K in keyof T as NewKey]: ... }
• Modifier removal — -readonly, -? to remove modifiers
• Template literal types — \${A}-${B}`` creates string literal unions
• Intrinsic string types — Uppercase<T>, Lowercase<T>, Capitalize<T>, Uncapitalize<T>
• Recursive types — types that reference themselves

Key Patterns