Regex to check if the first character is uppercase

Question

I'm trying to check that the first character of a username is capital, the following can be letters or numbers and at most 20 characters long. Can someone explain why my syntax is wrong?

/^[A-z][a-z0-9_-]{3,19}$/

Answer 1

Your first Z is not a capital Z.

/^[A-Z][a-z0-9_-]{3,19}$/

Answer 2

Why can't you let the poor users pick their own usernames? What you should do is convert all caps to lowercase.

"User Name".toLowerCase();

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But if you are truly evil, you should change that z to a Z:

/^[A-Z][A-Za-z0-9_-]{3,19}$/