JS Object.map

objectmap.js

const obj = { foo: 'hello', bar: 'world' }

const updatedObj = Object.fromEntries(
  Object.entries(obj).map(([key, val]) => [
    key,
    val.toUpperCase(),
  ]),
)

// {foo: "HELLO", bar: "WORLD"}

for the adventurous:

Object.map = (obj, cb) => Object.fromEntries(
  Object.entries(obj).map(([key, val]) => [
    key,
    cb(val),
  ]),
)

const obj = { foo: 'hello', bar: 'world' }

Object.map(obj, val => val.toUpperCase())