exec uglifyJS with php

I try to exec a simple cmd (which works on my terminal server), but not in my php script. I use UglifyJS2. It install in my /home/MY_USER/node_modules/uglify-js/

I have chmod the symlink like here: calling node and uglifyjs from Php context. But

exec(/usr/bin/node /usr/bin/uglifyjs ...);

or

exec(/usr/bin/uglifyjs ...);

doesn't work.

I haven't chmod my /home/ of course, but it's maybe the reason why doesn't works?

How can I do exec uglify by my php?

After fixing the syntax errors the apache (or web server) user will need exec permissions for the dir and bin. Why not install it in /usr/bin?