You could use rsync (it also does local copy)
rsync -r --ignore-existing --include=*/ --include=*.js --exclude=* source/ destination
-r
to recurse into directories,--ignore-existing
to ignore existing files in destination,- the
include
andexclude
filters mean: include all directories, include all *.js files, exclude the rest; the first include is needed, otherwise the final exclude will also exclude directories before their content is scanned.
Finally, you can add a -P
if you want to watch progress, a --list-only
if you want to see what it would copy without actually copying, and a -t
if you want to preserve the timestamps.
This is not related, but I learned the rsync command recently, when I moved 15 years of documents from one partition to another. Confident that my files were there, I then wiped the old partition and put some other stuff in there; I realized later that I lost all the timestamps, and discovered the -t flag. Just wanted to share my distress :'(