Module ulid/mod

Utilities for generating and working with Universally Unique Lexicographically Sortable Identifiers (ULIDs).

To generate a ULID use the ulid function. This will generate a ULID based on the current time.

import { ulid } from "@std/ulid";

ulid(); // 01HYFKMDF3HVJ4J3JZW8KXPVTY
Copy

ulid does not guarantee that the ULIDs will be strictly increasing for the same current time. If you need to guarantee that the ULIDs will be strictly increasing, even for the same current time, use the monotonicUlid function.

import { monotonicUlid } from "@std/ulid";

monotonicUlid(); // 01HYFKHG5F8RHM2PM3D7NSTDAS
monotonicUlid(); // 01HYFKHG5F8RHM2PM3D7NSTDAT
Copy

Because each ULID encodes the time it was generated, you can extract the timestamp from a ULID using the decodeTime function.

import { decodeTime, ulid } from "@std/ulid";
import { assertEquals } from "@std/assert";

const timestamp = 150_000;
const ulidString = ulid(timestamp);

assertEquals(decodeTime(ulidString), timestamp);
Copy