extract strings between last two slashes using regular expression in javascript

Question

I want to extract the string between last two string using a regular expression. I cannot seem to be able to come up with the right expression, if someone could help me that wou

Answer 1

Since you only care about the last set of slashes, you start by matching anything
.*
then you want a literal slash
\/ (escaped since the slash would terminate the js regex)
now you want anything up to the next slash, which implies not a slash and _there must be something (one-or-more) and we'll put that in a capturing group so you can extract it.
([^/]+)
and followed by another literal slash
\/
then anything else (the file name?) that, again, does not include slashes
[^/]+

Putting that all together gives you the regex
/.*\/([^/]+)\/[^/]+/
and
"aa/bbbb/ccccc/eeee/fffff.jpg".match(/.*\/([^/]+)\/[^/]+/);
produces
["aa/bbbb/ccccc/eeee/fffff.jpg", "eeee"]
... the eeee is captured.

Answer 2

I know you said you wanted to use a regex but for those looking for a solution but don't require it to be a regex, you could do this simply by splitting the string:

 var originalString = 'aa/bbbb/ccccc/eeee/fffff.jpg';

 //convert to array
 var parts = originalString.split('/');

 //find the second to last item
 var lastPartOfPath = '';

 //make sure there are more than one part
 if (parts.length > 1) {
      lastPartOfPath = parts[parts.length-2];
 }