Object mapping

objectmap.js

const odd = { a: 1, b: 3 };

const even = Object.entries(odd).reduce((object, pair) => {
  const [key, value] = pair;
  object[key] = value + 1;
  return object;
}, {});

console.log(even); // => { a: 2, b: 4 }

A suggestive refactor:

const odd = { a: 1, b: 3};

const kvmap = (f,o) => Object.entries(o).reduce((object, [k,v]) => {
object[k] = f(v);
return object;
}, {});

const even = kvmap(x => x+1, odd);

console.log(even); // => {a: 2, b: 4}