Which kind of Collection (Map, Set, WeakMap, WeakSet) is this JavaScript value? Works cross-realm, without `instanceof`, and despite Symbol.toStringTag.

TypeScript Array, Object, Map, Set, Union, Enum utils

Same as JSON but with added support for `Date`, `undefined`, `Map`, `Set`, and more.

Javascript data structures (e.g., Map, Set) that support deep object equality

ES Map/Set-compatible implementations with customizable equality semantics & supporting operations

LensMCP container/memory mutation tracking (Map/Set/Array instrumentation).

The fastest deep equal with ES6 Map, Set and Typed arrays support.

Skiplist-based sorted map & set implementation

n-D spatial indexing data structures with a shared ES6 Map/Set-like API

The fastest deep equal with ES6 Map, Set and Typed arrays support.

Signal-aware native Array, Map, Set, and Object collections

JavaScript's keyed collections (Map & Set) with SameValue semantics!

SuperJSON-based payload converter for Temporal workflows. Properly serialize and deserialize complex types like Date, Map, Set, and BigInt.

Shim to provide Map, Set, and WeakMap if they're not available, with non-leaky O(1) lookup WeakMaps

Lightweight deep clone supporting Date, Map, Set, RegExp, typed arrays, and circular references

Same as JSON but with added support for `Date`, `undefined`, `Map`, `Set`, and more.

Cancel changes to JavaScript object values (add/update/delete properties, add item into Map/Set, etc.)

High performance tuples for Map/Set indexing, NestedMap/NestedSet, and trees.

The boundary codec for SignalX — how Date, Map, Set, BigInt and custom types survive every server↔client boundary: the SSR state blob, resume boundary props, the cache seed, and the server-function RPC wire

Json with Map, Set, Date and cycle