@std/ulid

Overview Jump to heading#

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

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

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);

Add to your project Jump to heading#

deno add jsr:@std/ulid

See all symbols in @std/ulid on

What is a ULID? Jump to heading#

A ULID (Universally Unique Lexicographically Sortable Identifier) is a 26-character string that serves as a unique identifier. It combines a timestamp with random data, making it both unique and sortable based on the time of creation. ULIDs are designed to be URL-safe and can be used in various applications, such as databases and distributed systems.

Why use @std/ulid? Jump to heading#

Use when you need unique, time-sortable IDs that are easy to generate and share. Great for databases, distributed systems, and user-facing tokens.

Tips Jump to heading#

• Use monotonicUlid() when you need strictly increasing values within the same millisecond.
• You can extract the timestamp with decodeTime(ulid) to aid debugging.