This project has a build process to transpile es2015 code down to es5 prior to release. Feel free to use as much as2015 (and object spread) in your source as you'd like.
Once you're ready to publish, simply run make publish. Make will transpile your source and put the
output in dist/index.js. Then, it'll publish your changes to npm.
If you'd like to make a build but not publish, run make build. Also, make clean is a thing too.