Angular4.x Module not found: Error: Can't resolve 'classlist.js'
remove the current package,
npm uninstall classlist.js --save
npm cache verify
npm install classlist.js --save-exact
You're importing a polyfill that is not included by default. You have to install it as a dependency first. How to do that is in a comment on the same line that imports it:
// Run `npm install --save classlist.js`.
The same goes for the
web-animations-js polyfill if you haven't done so already.