once

The module has zero dependencies, keeping the package minimal and reducing bloat, as emphasized in its philosophy of solving the single-use problem cleanly.

Offers both permissive caching with once() and strict error-throwing with once.strict(), allowing developers to choose between safety and debugging, as shown in the greet function example.

Provides fn.called and fn.value properties to check invocation status and retrieve cached results, aiding in control flow and debugging, as documented in the usage section.

Can be used directly or via Function.prototype extension for chaining, making it simple to wrap callbacks in existing Node.js code, though the prototype feature adds complexity.