uuid v4 regex

uuidv4test.js

import { v4 as uuid } from 'uuid';

export function generateId() {
  return uuid();
}

const v4 = new RegExp(/^[0-9A-F]{8}-[0-9A-F]{4}-4[0-9A-F]{3}-[89AB][0-9A-F]{3}-[0-9A-F]{12}$/i);

console.log(generateId().match(v4));
//console.log(generateId().length)
//console.log('new way')
//console.log(generateId().length)
//console.log('new way, chopped')
//console.log(generateId().split('-')[0])
//console.log('old way')
//const generateNumber = () => Math.ceil(Math.random() * 100)
//console.log(`${generateNumber()}${generateNumber()}${generateNumber()}${generateNumber()}`)
// run with $ node_modules/.bin/babel-node testuuid.js

@gastrodon the alias is common, since it is just the version and v4 is not a good naming. But I agree that generateId is not the best thing here since you can alias the v4 as generateId and will be the same outcome.
To me looks like this was part of a bigger file and was just extracted the meaningful parts for the test.

I had to change the regex to lowercase as that seems to be what v4 is creating for me.

[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}

supporting lower or upper case

^[0-9(a-f|A-F)]{8}-[0-9(a-f|A-F)]{4}-4[0-9(a-f|A-F)]{3}-[89ab][0-9(a-f|A-F)]{3}-[0-9(a-f|A-F)]{12}$

The trailing /i means a case insensitive search. RE the last two comments.

@juanmartinez-viamericas A capture group (the parentheses) is not allowed in a range (the brackets), so your regex allows to put parentheses and pipres in uuids. And your "insensitive regex without flag" doesn't allow this range [89ab] in uppercase.

/^[0-9(a-f|A-F)]{8}-[0-9(a-f|A-F)]{4}-4[0-9(a-f|A-F)]{3}-[89ab][0-9(a-f|A-F)]{3}-[0-9(a-f|A-F)]{12}$/
  .test('376)5f8c-e686-4b(9-a85b-7e31|8f4062c') // returns true
//          ^            ^           ^
/^[0-9(a-f|A-F)]{8}-[0-9(a-f|A-F)]{4}-4[0-9(a-f|A-F)]{3}-[89ab][0-9(a-f|A-F)]{3}-[0-9(a-f|A-F)]{12}$/
  .test('376a5f8c-e686-4b79-A85b-7e31e8f4062c') // returns false
//                          ^

@gastrodon the alias is common, since it is just the version and v4 is not a good naming. But I agree that generateId is not the best thing here since you can alias the v4 as generateId and will be the same outcome. To me looks like this was part of a bigger file and was just extracted the meaningful parts for the test.

I think the alias here is just to make it concrete to the user that the uuid API returns a version 4 UUID.