Beyond Any and Unknown
TypeScript’s type system is Turing complete. Leveraging its full static analysis capability eliminates entire classes of runtime errors.
Conditional Types & infer
Conditional types allow types to be selected based on dynamic type checks.
type UnpackPromise<T> = T extends Promise<infer U> ? U : T;
type ResolvedNumber = UnpackPromise<Promise<number>>; // number
type DirectString = UnpackPromise<string>; // string
💡 Best Practice
Use unknown instead of any whenever dealing with external inputs, forcing explicit validation schemas before dereferencing properties.
Template Literal Types
Template literal types allow string manipulation directly inside the type system:
type EventName = 'click' | 'hover';
type ElementType = 'button' | 'card';
type DynamicHandler = `on${Capitalize<EventName>}${Capitalize<ElementType>}`;
// "onClickButton" | "onClickCard" | "onHoverButton" | "onHoverCard"
Summary
Advanced type definitions drastically improve IDE autocomplete and developer confidence across large codebases.