How to Validate a UUID with Regular Expressions in JavaScript

Let’s see how we can validate UUIDv4 using regular expressions in JavaScript.

Suppose we’re using the uuid npm package to generate a UUID.

import { v4 as uuidv4 } from 'uuid';
uuidv4(); // '2808f161-0f83-4382-8d50-37530fcc9dbe'

If you want to randomly generate a UUID online, check out uuidtools.com.

1. Create a regular expression to match UUIDv4

A UUID is a 36 character string containing 32 hexadecimal characters and 4 hyphens.

Below is a regular expression that will match a Version 4 UUID.

const regex = /^[a-z,0-9,-]{36}$/;

• ^ matches the beginning of the input
• [a-z,0-9,-] matches lowercase letters, numbers, and hyphens
• {36} requires the length to be 36 characters
• $ matches the end of the input

If the location of the hyphens needs to follow the standard UUIDv4 format, you can use the following regular expression:

const regex = /^[a-z,0-9]{8}-[a-z,0-9]{4}-4[a-z,0-9]{3}-[89AB][a-z,0-9]{3}-[a-z,0-9]{12}$/;

2. Validate a UUID using regular expression

We can easily validate a UUID using the test() method, which matches some input string against a regular expression literal.

function isValidUuid(str) {
  const regex = /^[a-z,0-9,-]{36}$/;
  return regex.test(str)
}

If you’re curious about the regex, I’d recommend using regex101.com to investigate and test regular expressions.