Extra-lazy is a TypeScript/JavaScript library that provides lazy evaluation utilities, allowing values and functions to be computed only when needed and cached for subsequent use. It's designed for developers working with TypeScript or JavaScript who want to optimize performance by deferring expensive computations until they're actually required. The library offers various lazy evaluation functions including lazy, weakLazy, lazyFunction, lazyAsyncFunction, and lazyStatic, with the latter mimicking React hooks' behavior for static memoization.