Object.mapEntries, Object.mapValues, Object.mapKeys

ObjectMap.js

Object.mapEntries = (obj, fn) =>
	Object.assign({}, ...Object.entries(obj).map(e => fn(e, obj)).map(([k, v]) => ({ [k]: v })));

Object.mapValues = (obj, fn) =>
	Object.mapEntries(obj, ([k, v]) => [k, fn(v, obj)]);

Object.mapKeys = (obj, fn) =>
	Object.mapEntries(obj, ([k, v]) => [fn(k, obj), v]);