Regex check if a file has any extension

Question

I am looking for a regex to test if a file has any extension. I define it as: file has an extension if there is no slashes present after the last ".". The slashes are always backslashes.

I started with this regex

.*\..*[^\\]

Which translates to

.*          Any char, any number of repetitions 
\.          Literal .
.*          Any char, any number of repetitions 
[^\\]       Any char that is NOT in a class of [single slash]

This is my test data (excluding ##, which is my comments)

\path\foo.txt            ## I only want to capture this line
\pa.th\foo               ## But my regex also captures this line <-- PROBLEM HERE
\path\foo                ## This line is correctly filtered out

What would be a regex to do this?

Answer 1

Your solution is almost correct. Use this:

^.*\.[^\\]+$

Sample at rubular.

Answer 2

I wouldn't use a regular expression here. I'd split on / and ..

var path = '\some\path\foo\bar.htm',
    hasExtension = path.split('\').pop().split('.').length > 1;

if (hasExtension) console.log('Weee!');

Here goes a more simple function to check it.

const hasExtension = path => {
    const lastDotIndex = path.lastIndexOf('.')
    return lastDotIndex > 1 && path.length - 1 > lastDotIndex
}

if (hasExtension(path)) console.log('Sweet')

Answer 3

You can also try even more simpler approach:

(\.[^\\]+)$

Details:

$      = Look from the end of string
[^\\]+ = Any character except path separator one or more time
\.     = looks for <dot> character before extension

Live Demo