Identifiers

ransu.uuid(); // v4
ransu.uuid.v7(); // time-sortable
ransu.nanoid(); // 21 URL-safe characters
ransu.ulid({ monotonic: true });
ransu.token(32); // a base64url secret
ransu.otp(6); // '042317'
ransu.password(16, { symbols: true });

All of them draw from the platform CSPRNG by default, whichever entry point you came through.

Which identifier

Need	Use
A database primary key	uuid.v7() — sorts by time, so indexes stay compact
A short URL-safe id	nanoid()
A sortable id shorter than a UUID	ulid()
A derived, stable id	uuid.v5(name, namespace)
A session token or secret	token()
Compatibility with existing data	whichever version that data uses

UUID: every version

RFC 9562 defines v1 through v8, and all of them are here.

Version	What it is
v1	60-bit timestamp, clock sequence and node ID
v2	DCE Security. Included for completeness, not recommended
v3	MD5 of a namespace and a name — deterministic
v4	122 random bits. The default
v5	SHA-1 of a namespace and a name — prefer this over v3
v6	v1 reordered so byte order matches time order
v7	Unix milliseconds plus randomness. Sorts chronologically
v8	Custom: your own 122 bits

Plus NIL, MAX, parse, stringify, validate, version, compare, timestamp, v1ToV6 and v6ToV1.

Names and argument order match the uuid package, so it is a drop-in replacement:

ransu.uuid.v5("python.org", ransu.uuid.NAMESPACE.DNS);
// '886313e1-3b8a-5372-9b90-0c9aee199e5d'

No MAC address

JavaScript cannot read one, so v1 and v6 use a random node ID with the multicast bit set, exactly as RFC 9562 §6.10 requires.

Monotonic within a millisecond

v7 uses the RFC 9562 method-3 counter, so identifiers made in the same millisecond still increase. When the counter runs out it borrows the next millisecond rather than repeating.

Deterministic identifiers for tests

Pass an engine and the identifier becomes reproducible. Each engine keeps its own clock and node state, so a fresh seeded engine always replays the same way:

import { xoshiro128pp } from "ransu/engine";

uuid.v4({ engine: xoshiro128pp(1) });
uuid.v7({ engine: xoshiro128pp(1), now: 1_700_000_000_000 });

Do this in tests only. An identifier drawn from a seeded engine is predictable by anyone who can guess the seed.