slick-array
Native JavaScript Array, but extended with custom indexing and group support for super-fast lookups.
array.prototype.at
An ES-spec-compliant (proposed) Array.prototype.at shim/polyfill/replacement that works as far down as ES3
hasharray
A data structure that combines a hash and an array for fast dictionary lookup and traversal by complex keys.
locate-path
Get the first path that exists on disk of multiple paths