ID generation in JavaScript is the process of creating identifiers, usually strings or numbers, that distinguish one record, element, or session from another in a JavaScript program. Common approaches include random numbers, timestamps, universally unique identifiers (UUIDs), and third-party libraries such as nanoid. The right method depends on whether the ID must be secure, short, sortable, or unique across systems.
Overview
Applications need identifiers for database rows, DOM elements, uploaded files, orders, and sessions. A good identifier is unique, hard to guess when exposed publicly, and suited to how it will be stored or displayed. JavaScript has no single built-in "ID" function, so developers choose between language features, the Web Crypto API, and external packages.
Methods
Math.random()
Math.random() returns a pseudo-random number that can be converted into a string.
const id = Math.random().toString(36).slice(2);
It requires no dependencies, but it is not cryptographically secure and collisions are possible. It is suitable only for temporary or non-sensitive keys.
Date.now()
Date.now() returns the current time in milliseconds.
const id = Date.now();
The result is sortable by creation time. Two IDs created in the same millisecond can be identical, and the values are easy to guess.
crypto.randomUUID()
crypto.randomUUID() returns a version 4 UUID generated from a cryptographically secure random source.
const id = crypto.randomUUID();
It is available in modern browsers (secure contexts only, meaning HTTPS or localhost) and in Node.js 14.17 and later. It is widely regarded as the default choice.
nanoid
nanoid is a small third-party library that produces compact, URL-safe string IDs. The default length is 21 characters.
import { nanoid } from 'nanoid';
const id = nanoid();
It is commonly used for share links and short codes.
UUID version 7
UUID version 7 embeds a timestamp in the leading bits, so identifiers are roughly ordered by creation time. It is available through the uuid package.
import { v7 } from 'uuid';
const id = v7();
