cd ~
wget http://nodejs.org/dist/v6.2.1/node-v6.2.1-linux-armv6l.tar.gz
tar -xzf node-v6.2.1-linux-armv6l.tar.gz
node-v6.2.1-linux-armv6l/bin/node -v
The last command should print v6.2.1.
Now you can copy it to /usr/local
cd node-v6.2.1-linux-armv6l/
sudo cp -R * /usr/local/
For testing add /usr/local/bin to your path
export PATH=$PATH:/usr/local/bin
node -v
npm -v
This should print 6.2.1 and 3.9.3 for the versions of nodejs and npm. If you need a different version, just pick the one you like from the downloads.
Don't forget to add the PATH to your .bashrc to make it permanent.
To find the correct architecture, you can type uname -m
I now have node-v12.15.0-linux-armv6l downloaded to my Raspberry Pi Zero W as per these instructions. Now I get the error: 'You need to run "nvm install v12.15.0" to install before using it.'
I am completely new at this and learning as I go. When I try to run nvm install it looks at the nodejs source and not the local source. Any guidance would be greatly appreciated.