After Node v6.6.0 is out, I wanted to try it, but I don't want to replace my local Node v4 environment. I can use nvm, but that's too much for some simple tests. So I switched to Docker.

Just adding following alias to my .zshrc file, I can now run JavaScript file using Node 6.

alias node6="docker run -it --rm -v $(pwd):/code -w /code node:6.6 node"  
node6 hello.js  

I also added Node 4.

alias node4="docker run -it --rm -v $(pwd):/code -w /code node:4.5 node"