Cross-browser Class List
Originally forked from https://github.com/eligrey/classList.js with the difference that it has a package.json for nodejs/iojs projects:
classList.js is a cross-browser JavaScript shim that fully implements element.classList. Refer to [the MDN page on element.classList][1] for more information.
This works in every browser except IE 7 or earlier.
Install
npm i -S cross-class-list