How to use the keyof operator in TypeScript

The article delves into the use of the `keyof` operator in TypeScript, contrasting it with JavaScript's `Object.keys` method. While `Object.keys` returns an array of property keys for runtime objects, `keyof` operates at the type level, yielding a union of string literal types. This operator is integral to advanced TypeScript features such as generics, mapped types, and string literal types, enhancing type safety by allowing developers to define types based on object keys. The text explores various scenarios, including creating new types through the `keyof typeof` pattern, using `keyof` with TypeScript generics to enforce constraints, employing it in mapped types for transforming and remapping properties, and integrating it with utility types like `Record` and `Pick`. Moreover, it discusses the use of `keyof` in combination with template string literals introduced in TypeScript 4.1, enabling complex type compositions and property remapping. These capabilities allow for the creation of maintainable and type-safe code by automatically adapting to changes in base types, thus preventing runtime errors.