Table of contents What is Fundamental? Function once chain Object keys(), values(), entries() hasOwn() guards �Object.prototype.toString() �Primitive, object Nullish(Nil) �Falsy, Truthy Array includes �shuffle countBy groupBy misc assert (invariant) predicates URL(SearchParams), encodeURI(Component) to types UnionToIntersection hooks useCallbackRef useIsomorphicLayoutEffect useEvent useHydrated useControllableState useList useCheckList react utils mergeRefs mergeProps