Explain advanced generic constraints and conditional types.

Advanced generics combine constraints, conditional types, and inference for powerful type transformations. Generic Constraints: interface Lengthwise { length: number; } function loggingIdentity(arg: T): T { console.log(arg.length); return arg; } loggingIdentity('hello'); // Works loggingIdentity([1, 2, 3]); // Works loggingIdentity(3); // Error: number does not have length Conditional Types: type NonNullable = T extends null | undefined ? never : T; type ApiResponse = T extends string ? { message: T } : { data: T }; // Usage type StringResponse = ApiResponse; // { message: string } type NumberResponse = ApiResponse; // { data: number } Advanced Pattern with Infer: type ReturnType = T extends (...args: any[]) => infer R ? R : never; type Parameters = T extends (...args: infer P) => any ? P : never; // Extract nested array type type Flatten = T extends (infer U)[] ? U : T; type StringArray = Flatten; // string type NumberType = Flatten; // number Benefits: • Enable complex type transformations • Create flexible, reusable type utilities • Provide compile-time guarantees • Support advanced API design patterns.