es-set
An ES-spec-compliant Set shim/polyfill/replacement that works as far down as ES3
es-map
An ES-spec-compliant Map shim/polyfill/replacement that works as far down as ES3
date
ES spec-compliant `Date` shim/polyfill/replacement that works as far down as ES3
array.prototype.at
An ES-spec-compliant (proposed) Array.prototype.at shim/polyfill/replacement that works as far down as ES3