Advanced Typescript Type Level

Conditional types enable dynamic type transformations by testing a type condition and returning different types based on the result. Use the syntax `Type extends Condition ? TrueType : FalseType` to create types that adapt to their inputs, catching type errors at compile-time before runtime.

Template literal types construct new string types by combining literal strings with type variables using backtick syntax. They enable type-safe string manipulation and validation at compile-time, allowing you to generate precise types for API clients, schema validation, and string-based type inference.

The `infer` keyword captures types from conditional type branches, letting you extract nested or implicit types from function signatures, arrays, or generic structures. This pattern powers advanced type inference for utility types and enables sophisticated type-level reasoning without runtime overhead.

Mapped types iterate over object properties to create new types based on existing shapes. They transform interfaces into utilities like making all properties optional, readonly, or extracting specific property types, all resolved at compile-time with zero runtime cost.

Type-level inference has computational complexity limits and can cause editor slowdowns in deeply nested generics. Test performance with large unions and recursive types; use simpler conditional branches when possible and validate that complex type logic compiles predictably across your codebase.