EasyValidation
Valid Username Checker
Write a regex that validates usernames: they must start with a letter, be 3-16 characters total, and contain only letters, digits, or underscores.
Need a syntax reminder? Read our detailed guide on the Valid Username Checker Regex Pattern.
//
john_doe / a1 / 1john / valid_user123 / way_too_long_username_here / jo / _user
Test cases
- john_doeexpect match
- valid_user123expect match
- a1expect no match
- 1johnexpect no match
- way_too_long_username_hereexpect no match
- joexpect no match
- _userexpect no match
How to Solve this Regex Challenge
To complete the Valid Username Checker challenge, you must write a regular expression pattern that satisfies all specified test cases.
Steps to Complete:
- Analyze the Requirements: Read the description and review the list of test cases below. Identify which strings must be matched (green markers) and which must be rejected (red markers).
- Draft Your Pattern: Enter your regex in the interactive editor. Use the provided Hint button if you get stuck.
- Verify: The test cases panel will update in real-time as you type, showing which strings match your current expression.
- Review the Solution: Once you successfully pass all test cases, review the explanation to understand the logic behind the solution.