Regex for file extension

Note

Group 1 is the extension. For archive.tar.gz it is gz, the last one.

Matches in the example

• ".pdf"
• ".gz"
• ".JPEG"

Token by token

1. \. the character “.”
2. ( a capturing group
3. [a-z0-9]{1,10} one of: “a” to “z” or “0” to “9”, between 1 and 10 times, as many as possible
4. ) end of group
5. $ the end of the string (or line, with the m flag)

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