What is the regex pattern for file extension?

The regex pattern for file extension is: ^.+\.([a-zA-Z0-9]{1,10})$.

How does the file extension regex work?

^: Start of string. .+: One or more characters (filename). \.: Literal dot before extension. ([a-zA-Z0-9]{1,10}): Extension: 1-10 alphanumeric characters (captured). $: End of string.

Regex for File Extension

Matches filenames and extracts the file extension. Captures extensions up to 10 characters long.

Pattern

/^.+\.([a-zA-Z0-9]{1,10})$/

Pattern Breakdown

Token	Explanation
^	Start of string
.+	One or more characters (filename)
\.	Literal dot before extension
([a-zA-Z0-9]{1,10})	Extension: 1-10 alphanumeric characters (captured)
$	End of string

Test Examples

Input	Match?
document.pdf	Match
archive.tar.gz	Match
image.png	Match
noextension	No match
.hidden	No match

Common Use Cases

File upload validation
File type filtering
Directory listing

Variations

\.(jpe?g|png|gif|svg|webp)$

Specific image extensions

\.(js|ts|jsx|tsx)$

JavaScript/TypeScript files

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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