Array map on objects.

obj-map.js

function omap(object, cb) {
  return Object.fromEntries(Object.entries(object).map(cb));
}

const mappable = {
  map(cb) {return omap(this, cb)}
}

const abc = {
  a: 1,
  b: 2,
  c: 3,
  d: 4,
  e: 5,
  // ...
  __proto__: mappable
}

abc.map(([key, value]) => [key, value + 10]) //=> {a: 11, b: 12, c: 13, d: 14, e: 15, ...}