typescript

TypeScript is a typed superset of JavaScript that compiles to plain JavaScript. It adds optional static typing, interfaces, and other features that help catch errors at compile time, improve IDE support, and make code more maintainable.

TypeScript includes primitive types (string, number, boolean, null, undefined, symbol, bigint), array types, tuple types, object types, and special types like any, unknown, void, and never.

Both define object shapes, but interfaces can be extended and merged (declaration merging), while type aliases can represent unions, tuples, and primitives. Use interfaces for objects/classes and type aliases for unions or complex types.

Union types (A | B) represent values that can be one of several types - use when a value could be different types. Intersection types (A & B) combine multiple types into one - use when a value must satisfy all types simultaneously.

Functions can be typed by annotating parameters and return type. TypeScript infers return types when possible. Use function type expressions for callbacks, optional/default parameters for flexibility, and overloads for multiple signatures.