"Polymer custom elements are authored in HTML files, which limits you to plain JavaScript/CSS (and language features supported by today’s browsers). In comparis

"Polymer custom elements are authored in HTML files, which limits you to plain JavaScript/CSS (and language features supported by today’s browsers). In comparison, Vue’s single file components allows you to easily use ES2015+ and any CSS preprocessors you want." This is incorrect. It's easy to use ES2015+, TypeScript and CSS preprocessors in Polymer.