What is the regex pattern for username?

The regex pattern for username is: ^[a-zA-Z][a-zA-Z0-9._-]{2,29}$.

How does the username regex work?

^: Start of string. [a-zA-Z]: Must start with a letter. [a-zA-Z0-9._-]{2,29}: 2-29 more characters (letters, digits, dot, underscore, hyphen). $: End of string.

Regex for Username

Matches usernames: 3-30 characters, starts with a letter, allows letters, digits, dots, underscores, and hyphens.

Pattern

/^[a-zA-Z][a-zA-Z0-9._-]{2,29}$/

Pattern Breakdown

Token	Explanation
^	Start of string
[a-zA-Z]	Must start with a letter
[a-zA-Z0-9._-]{2,29}	2-29 more characters (letters, digits, dot, underscore, hyphen)
$	End of string

Test Examples

Input	Match?
john_doe	Match
user123	Match
a.b-c	Match
1user	No match
ab	No match

Common Use Cases

User registration validation
Profile URL slugs
Social media handles

Variations

^[a-zA-Z0-9_]{3,20}$

Alphanumeric and underscore only

Other Regex Patterns

Email Address US Phone Number International Phone Number URL IPv4 Address IPv6 Address Date (MM/DD/YYYY)Date (ISO 8601 YYYY-MM-DD)Time (HH:MM, 24-hour)Credit Card Number US Social Security Number US ZIP Code

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