Best way to persist user preferences with npm/nodejs command line utility

I'm writing a nodejs cli utility (NPM module intended to be installed globally) that will need to store some user-supplied values. What is the best way to store these values on a system?

For example, should I create my own config file under say: /etc/{my-utility-name}/conf.json and have this directory+file initialized in my install script

(https://npmjs.org/doc/misc/npm-scripts.html)