core-js is the more common of the two in our index: it runs on 19,221 websites against 27 for pickadate.js, and 17 sites use both. Counts come from real scans, not vendor claims.
core-js is a modular standard library for JavaScript, with polyfills for cutting-edge ECMAScript features.
Mobile-friendly, responsive, and lightweight jQuery date & time input picker.
17 sites run both core-js and pickadate.js. That is 63% of the sites using pickadate.js, the smaller of the two.
Want to know which one a particular site uses? Look it up and see its whole stack, or compare two sites side by side.