Regex Editor & Tester

Matches package names starting with a lowercase letter, hyphen, or underscore, followed by 1 to 21 characters that exclude uppercase letters and whitespace, giving a total length of 2-22 characters. Typically used to validate npm-style package names in JavaScript, enforcing lowercase naming conventions without spaces. With the 'gm' flags, it can validate multiple package names across multiple lines in a single input.