My regex code is right, but the challenge won't pass

JavaScript
1

Hey there, I am doing a regex challenge on the beta site. Here it is: https://beta.freecodecamp.com/en/challenges/regular-expressions/restrict-possible-usernames. I have taken my regex and put it into this site and all the parameters pass: https://regex101.com/r/fqeFDT/1. If I have made an error can someone please point it out? I am failing the 1st and 4th check.

And here is my code:

let username = "JackOfAllTrades";
let userCheck = /^[a-z]{2}([a-z]+)?(\d+)?$/gi; // Change this line
let result = userCheck.test(username);
2

I’m not sure why your regex is failing the tests, but it might have something to do with the g flag. I tried a couple of different regexs that met the requirements without using the g flag, and they both passed the tests. (Basically use {1,} instead of combining + and g to match one or more)

3

Remove the g flag - the g flag is for incremental matching - it is not needed for this exercise - it causes test cases to fail because the same regex variable is used for every test case

This regex is a simpler equivalent of yours: /^[a-z]{2,}\d*$/i

However the exercise has issues - username “007” should be allowed since it has more than 2 characters and has numbers only at the end - either the test case should be corrected or the exercise statement should be updated to restrict usernames to start with a letter or possibly 2 letters

2 Likes
4

Thanks for the help. Could you explain what {2,} means?

5

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp#quantifiers

The general brace expression is {m,n} that matches between m and n occurrences of the preceding item - no n means match at least m occurrences - no m means match at most n occurrences - {2,} means match at least 2 occurrences - {,2} means match at most 2 occurrences - you know what {2} means

1 Like
6

This let me past the test too,

let userCheck = /[a-z][a-z]/gi;

but it feels incorrect… Why didn’t I had to declare \d?

7

I think I get it,

“kk66d” should not pass, but it does with my code and in the test there there are only strings given with numbers at the beginning or end.

8

My code is right but it won’t let me pass the test, here is my code:

/[a-z][a-z]\w*\w\w/gi

result:Your regex should match JACK
Your regex should match RegexGuru

9

My problem resolved after I changed my regex to

/[a-z][a-z]\w*\w\w/i
10

Hi Alimama,
even though your code passes the test, it’s not quite correct. Here are few usernames that shouldn’t go through, but your RegEx doesn’t restrict them:

  • 1Jack (Since the only digits in the username have to be at the end)
  • Ja33ck (Digits should be at the end)
  • Ja (should pass)
    etc…

Your RegEx allows digits in the begging and in the middle, and makes the word at least 4 characters long.

The easiest solution to the challenge should be:

/[1]{2,}\d*$/i

where:

^[a-z] guarantees that your username starts with letter;
^[a-z]{2,} guarantees that it starts with letters and is at least 2 characters long;
\d* says it can have 0 or more digits.
\d*$ guarantees that digits are only at the end.
i - ignore case.

Hope this helps,
Good luck.

  1. a-z ↩︎

8 Likes
11

That is an excellent breakdown to explain the solution! Thank you!

12

why is there no g flag?

13

Can’t tell exactly, but almost every time I’m using ‘g’ flag some of the tests fail (even tho I know that RegEx is correct).

14

The most efficient regex I could come up with was /^[a-z].\d*?/i…