Install

npm install ulid-generator

ULID

ULID is Universally Unique Lexicographically Sortable Identifier. A ULID consists of 128 bits, Out of which 48 bits represent time and 80 bits are of randomness.

Deep dive :

• https://github.com/ulid/spec
• https://sudhir.io/uuids-ulids
• https://blog.daveallie.com/ulid-primary-keys

Usage

const { ulid } from "ulid-generator"

import { ulid } from "ulid-generator"

Crockford Base32 format

ulid()
Output: 01HR2TC52K381F3363F1SF181Y

Formatted as UUID

ulid({encode:"uuid"})
Output: 18E05A8C-DA6F-1F23-0207-A2B4F97F7821

(Postgres specific) : Storing in DB as uuid format takes less space on disk. Postgres has specific UUID type, which stores it in binary rather than string. Thus, when stored as UUID type it take 128bits (16 Bytes) rather than 26 Bytes in case of ULID as Crockford base 32 format or 36 Bytes in case of UUID as string.

Base32 format

ulid({encode:"base32"})
Output: 01HO2QMKRN1T1K2TD1AQ2E31C3

Base64 format

ulid({encode:"base64"})
Output: 000c8FuzXqBdBqBmBFGBPHB4JB

ULID Monotonic Increment in a millisecond

Generating mulitple ULIDs in a millisecond increments the previous ULID, when monotonic flag is set in passed options.

ulid({encode:"Crockford",monotonic:true})

Output:
01HR42P8DA3H141HC3R1KA2W12
01HR42P8DA3H141HC3R1KA2W13
01HR42P8DA3H141HC3R1KA2W14

ulid({encode:"uuid",monotonic:true})

Output:
18E082B2-1A15-454D-3627-353961464139
18E082B2-1A15-454D-3627-35396146413A
18E082B2-1A15-454D-3627-35396146413B

Test