Regex to get a filename from a url

Question

I am trying to write a regex to get the filename from a url if it exists.

This is what I have so far:

(?:[^/][\d\w\.]+)+$

So from the url http://www.foo.com/bar/baz/filename.jpg, I should match filename.jpg

Unfortunately, I match anything after the last /.

How can I tighten it up so it only grabs it if it looks like a filename?

Answer 1

This one works well for me.

(\w+)(\.\w+)+(?!.*(\w+)(\.\w+)+)

Answer 2

The examples above fails to get file name "file-1.name.zip" from this URL:

"http://sub.domain.com/sub/sub/handler?file=data/file-1.name.zip&v=1"

So I created my REGEX version:

[^/\\&\?]+\.\w{3,4}(?=([\?&].*$|$))

Explanation:

[^/\\&\?]+          # file name - group of chars without URL delimiters
\.\w{3,4}           # file extension - 3 or 4 word chars
(?=([\?&].*$|$))    # positive lookahead to ensure that file name is at the end of string or there is some QueryString parameters, that needs to be ignored

Answer 3

(?:.+\/)(.+)

Select all up to the last forward slash (/), capture everything after this forward slash. Use subpattern $1.

Answer 4

Non Pcre

(?:[^/][\d\w\.]+)$(?<=\.\w{3,4})

Pcre

(?:[^/][\d\w\.]+)$(?<=(?:.jpg)|(?:.pdf)|(?:.gif)|(?:.jpeg)|(more_extension))

Demo

Since you test using regexpal.com that is based on javascript(doesnt support lookbehind), try this instead

(?=\w+\.\w{3,4}$).+

Answer 5

I'm using this:

(?<=\/)[^\/\?#]+(?=[^\/]*$)

Explanation:

(?<=): positive look behind, asserting that a string has this expression, but not matching it.

(?<=/): positive look behind for the literal forward slash "/", meaning I'm looking for an expression which is preceded, but does not match a forward slash.

[^/\?#]+: one or more characters which are not either "/", "?" or "#", stripping search params and hash.

(?=[^/]*$): positive look ahead for anything not matching a slash, then matching the line ending. This is to ensure that the last forward slash segment is selected.

Example usage:

const urlFileNameRegEx = /(?<=\/)[^\/\?#]+(?=[^\/]*$)/;

const testCases = [
  "https://developer.mozilla.org/en-US/docs/Web/API/MutationObserverInit#yo",
  "https://developer.mozilla.org/static/fonts/locales/ZillaSlab-Regular.subset.bbc33fb47cf6.woff2",
  "https://developer.mozilla.org/static/build/styles/locale-en-US.520ecdcaef8c.css?is-nice=true"
];

testCases.forEach(testStr => console.log(`The file of ${testStr} is ${urlFileNameRegEx.exec(testStr)[0]}`))