Regex for hashtag

Note

The u flag lets \p{L} match letters in any script. The lookbehind skips a # inside a word, like C#.

Matches in the example

• "#regex"
• "#日本語"
• "#100DaysOfCode"

Token by token

1. (?<! not preceded by (negative lookbehind)
2. [\w#] one of: a word character (letter, digit or _) or “#”
3. ) end of group
4. # the character “#”
5. [\p{L}\p{N}_]+ one of: a character in the Unicode property “L”, a character in the Unicode property “N” or “_”, one or more times, as many as possible

Other patterns

• Email address
• URL
• IPv4 address
• UUID
• Hex color
• Date (YYYY-MM-DD)
• Time (24-hour)
• US phone number
• Phone number (E.164)
• US ZIP code
• Credit card number
• URL slug
• Username
• Strong password
• HTML tag
• Semantic version
• MAC address
• JSON Web Token
• Hashtag
• @mention
• Number
• Leading and trailing whitespace
• Repeated word
• Blank lines
• Markdown link
• Quoted string
• Domain name
• File extension
• Base64
• Trailing comma