extractFileName.js

/* You have to extract a portion of the file name as follows:
Assume it will start with date represented as long number
Followed by an underscore
Youll have then a filename with an extension
it will always have an extra extension at the end

Inputs:
1231231223123131_FILE_NAME.EXTENSION.OTHEREXTENSION
1_This_is_an_otherExample.mpg.OTHEREXTENSIONadasdassdassds34
1231231223123131_myFile.tar.gz2

Outputs:
FILE_NAME.EXTENSION
This_is_an_otherExample.mpg
myFile.tar

Acceptable characters for random tests:
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-0123456789
The recommend way to solve it is using RegEx and specifically groups. */


class FileNameExtractor {
    static extractFileName (dirtyFileName) {
     return dirtyFileName.substring(dirtyFileName.indexOf("_")+1, dirtyFileName.lastIndexOf("."))  
    }
}