Is there some other setting that i need to make for the proxy for the zypper to work.
I would appreciate if there is any other way to install node.js in the system. I have tried installing from binary package nodejs-6.3.0-113.1.x86_64.rpm but it only install node but not the npm.
I am not quite understanding what you are trying to do.
You say you have openSUSE 12.1, but the repo is for SLE 12 SP1.
On openSUSE 12.1: That is way out of support and while it may be possible to find the OSS and non-OSS repos for it, it might be more difficult to find other repos that where available at that time.
On SLE 12 SP1: You re at the wrong forums. These are the openSUSE forums, not the SLES/SLED forums. Those are at https://forums.suse.com/forum.php (same username/password as here).
So please find out what you have on that system e.g. using
cat /etc/SuSE-release
and then ask at the correct forums, while not mixing repos from a different version.