uuidv7-js
v1.1.4
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UUIDv7 generator library for JavaScript, RFC 9562 compliant. Supports encoding/decoding UUIDs to custom alphabets.
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uuidv7-js
UUIDv7 generator library for JavaScript, RFC 9562 compliant. Supports encoding/decoding UUIDs to custom alphabets.
Installation
npm i uuidv7-js
Usage
import { UUIDv7, uuidv7, encodeUUIDv7, decodeUUIDv7 } from "uuidv7-js";
// Initialize a new UUIDv7 generator.
// You can pass a custom encoding alphabet here.
const uuid = new UUIDv7();
const id = uuid.gen(); // 018ef3e8-90e2-7be4-b4ea-4be3bf8803b7
const encoded = uuid.encode(id); // CANANjseoigQthQMd1VwC
const decoded = uuid.decode(encoded); // 018ef3e8-90e2-7be4-b4ea-4be3bf8803b7
const isValid = UUIDv7.isValid(id); // true
const timestamp = UUIDv7.timestamp(id); // 1713489088738
const date = UUIDv7.date(id); // 2024-04-19T01:11:28.738Z
// You can also use convenient function aliases if you don't need to use a custom alphabet.
const id = uuidv7(); // 018ef3e8-90e2-7be4-b4ea-4be3bf8803b7
const encoded = encodeUUIDv7(id); // CANANjseoigQthQMd1VwC
const decoded = decodeUUIDv7(encoded); // // 018ef3e8-90e2-7be4-b4ea-4be3bf8803b7
Create a new instance
const uuid = new UUIDv7(opts?: { encodeAlphabet?: string })
Creates a new UUIDv7
instance. By default it uses the Base58 alphabet to encode
and decode
UUIDs, but you can pass a custom alphabet (16-64 characters).
Instance methods
gen
gen(customTimestamp?: number) => string
Generates a new UUIDv7. You can provide a custom timestamp to be used instead of the current one.
genMany
genMany(amount: number, customTimestamp?: number) => string[]
Generates a custom amount of UUIDv7s. You can provide a custom timestamp to be used instead of the current one.
encode
encode(id: string) => string
Encodes a UUIDv7 using the alphabet passed to the constructor or the default one.
decode
decode(encodedId: string) => string | null
Decodes an encoded UUIDv7 using the alphabet passed to the constuctor or the default one. If the UUIDv7 is not valid, null
is returned.
decodeOrThrow
decodeOrThrow(encodedId: string) => string
Decodes an encoded UUIDv7 using the alphabet passed to the constuctor or the default one. If the UUIDv7 is not valid, an error is thrown.
Static methods
UUIDv7.isValid
UUIDv7.isValid(id: string) => boolean
Checks if the UUIDv7 is valid.
UUIDv7.timestamp
UUIDv7.timestamp(id: string) => number | null
Returns the timestamp part of the UUIDv7. If the UUIDv7 is not valid, null
is returned.
UUIDv7.date
UUIDv7.date(id: string) => Date | null
Returns the timestamp part of the UUIDv7 converted to Date
. If the UUIDv7 is not valid, null
is returned.
Function aliases
The library provides a few function aliases for convenience. You can use them without creating a new UUIDv7
instance:
| Function name | Instance method | Description |
| --------------------- | --------------- | --------------------------------------------------------------------------------------------- |
| uuidv7
| gen
| Generates a new UUIDv7. |
| encodeUUIDv7
| encode
| Encodes a UUIDv7 with the default Base58 alphabet. |
| decodeUUIDv7
| decode
| Decodes an encoded UUIDv7 from Base58 alphabet. Returns null if the encoded ID is invalid. |
| decodeOrThrowUUIDv7
| decodeOrThrow
| Decodes an encoded UUIDv7 from Base58 alphabet. Throws an error if the encoded ID is invalid. |
Implementation details
This library implements the RFC 9562 spec to generate UUIDv7s:
- if the current timestamp is ahead of the last stored one, it generates new
rand_a
andrand_b
parts; - if the current timestamp is behind the last stored one, it waits for the next valid timestamp to return a UUIDv7 with newly generated
rand_a
andrand_b
parts; - if the current timestamp is the same as the last stored one:
- it uses
rand_b
and thenrand_a
as randomly seeded counters, in that order.rand_b
is the primary counter, andrand_a
is used as the secondary one, whenrand_b
overflows its 62 bits (rare case). When used as a counter,rand_b
increments its previous random value by a random integer between 1 and 4,294,967,296 (2^32), andrand_a
increments its previous random value by 1, while generating a newrand_b
part. - if both counters overflow their bit sizes, the generation function waits for the next millisecond to return a UUIDv7 with newly generated random parts.
- it uses
This approach follows the method 2 of the "Monotonicity and Counters" section of the spec. It guarantees monotonicity and uniqueness per instance, and always keeps timestamp the same as Date.now()
value.
If you provide a custom timestamp, it will be used instead of the current one. Generation works differently in this case:
- if the custom timestamp is different from the last custom stored one, it generates new
rand_a
andrand_b
parts; - if the custom timestamp is the same as the last custom stored one, it uses
rand_b
and thenrand_a
as randomly seeded counters, in that order, just like the normal generation method. If bothrand_a
andrand_b
overflow, though, the generator creates newrand_a
andrand_b
parts. This breaks monotonicity per instance with custom timestamp, but ensures that a valid UUIDv7 is always returned. Keep in mind that this is an extremely rare case and should really never happen.
Field and Bit Layout
This is the UUIDv7 Field and Bit Layout, took from the spec linked above:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| unix_ts_ms |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| unix_ts_ms | ver | rand_a |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|var| rand_b |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| rand_b |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Description
unix_ts_ms
48 bit big-endian unsigned number of Unix epoch timestamp in milliseconds as per Section 6.1. Occupies bits 0 through 47 (octets 0-5).
ver
The 4 bit version field as defined by Section 4.2, set to 0b0111 (7). Occupies bits 48 through 51 of octet 6.
rand_a
12 bits pseudo-random data to provide uniqueness as per Section 6.9 and/or optional constructs to guarantee additional monotonicity as per Section 6.2. Occupies bits 52 through 63 (octets 6-7).
var
The 2 bit variant field as defined by Section 4.1, set to 0b10. Occupies bits 64 and 65 of octet 8.
rand_b
The final 62 bits of pseudo-random data to provide uniqueness as per Section 6.9 and/or an optional counter to guarantee additional monotonicity as per Section 6.2. Occupies bits 66 through 127 (octets 8-15).
Feedback
If you found a bug in the implementation, please open a new issue.
Alternatives
License
This project is licensed under the MIT License.