Type check values
The `is` project is a type-checking library for JavaScript and TypeScript that provides methods to validate whether values match specific types. It offers both type guards for conditional narrowing and assertion functions that throw errors on type mismatches, with extensive support for primitives, built-in objects, typed arrays, and custom predicates. The library is written in TypeScript, uses branded types to ensure proper type narrowing in guard functions, and is distributed as an npm package published by Sindresorhus with millions of weekly downloads.