flat
Take a nested Javascript object and flatten it, or unflatten an object with delimited keys
array.prototype.flat
An ES2019 spec-compliant `Array.prototype.flat` shim/polyfill/replacement that works as far down as ES3.
array.prototype.flatmap
An ES2019 spec-compliant `Array.prototype.flatMap` shim/polyfill/replacement that works as far down as ES3.