Perl is less like the shell. See grep - it doesn't take grep command line options.

You likely want:

    @ujs = grep { m![^/]*\.js! } @js;
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Also, in Perl, it's customary to write regular expressions between // or as m!! (or any other character pair after m). Using strings as regular expressions works, but usually it's written as:

       if($String =~ /[^\/]*\.js/ )
# or
       if($String =~ m![^/]*\.js! )
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