Simplistic recursive merge fn for JS

smplRecMerge.js

const recMerge = (objA, objB) => Object.entries(objB).reduce(
  (acc, [key, val]) => Object.assign(
    {},
    objA,
    { [key]: is(Object, val) ? recMerge(objA[key], val) : val }
  ),
  {}
);