freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/regular-expressions/restrict-possible-usernames.md

id, title, challengeType, forumTopicId

id	title	challengeType	forumTopicId
587d7db8367417b2b2512ba2	Restrict Possible Usernames	1	301363

--description--

Usernames are used everywhere on the internet. They are what give users a unique identity on their favorite sites.

You need to check all the usernames in a database. Here are some simple rules that users have to follow when creating their username.

1. Usernames can only use alpha-numeric characters.

2. The only numbers in the username have to be at the end. There can be zero or more of them at the end. Username cannot start with the number.

3. Username letters can be lowercase and uppercase.

4. Usernames have to be at least two characters long. A two-character username can only use alphabet letters as characters.

--instructions--

Change the regex userCheck to fit the constraints listed above.

--hints--

Your regex should match JACK

assert(userCheck.test('JACK'));

Your regex should not match J

assert(!userCheck.test('J'));

Your regex should match Jo

assert(userCheck.test('Jo'));

Your regex should match Oceans11

assert(userCheck.test('Oceans11'));

Your regex should match RegexGuru

assert(userCheck.test('RegexGuru'));

Your regex should not match 007

assert(!userCheck.test('007'));

Your regex should not match 9

assert(!userCheck.test('9'));

Your regex should not match A1

assert(!userCheck.test('A1'));

Your regex should not match BadUs3rnam3

assert(!userCheck.test('BadUs3rnam3'));

Your regex should match Z97

assert(userCheck.test('Z97'));

Your regex should not match c57bT3

assert(!userCheck.test('c57bT3'));

Your regex should match AB1

assert(userCheck.test('AB1'));

--seed--

--seed-contents--

let username = "JackOfAllTrades";
let userCheck = /change/; // Change this line
let result = userCheck.test(username);

--solutions--

let username = "JackOfAllTrades";
const userCheck = /^[a-z]([0-9]{2,}|[a-z]+\d*)$/i;
let result = userCheck.test(username);