What's the best way (most efficient) to turn all the keys of an object to lower case?

Question

I\'ve come up with

function keysToLowerCase (obj) {
  var keys = Object.keys(obj);
  var n = keys.length;
  while (n--) {
    var key = keys[n]; // \"cache\"         


        

Answer 1

const keysToLowerCase = object => {
  return Object.keys(object).reduce((acc, key) => {
    let val = object[key];
    if (typeof val === 'object') {
      val = keysToLowerCase(val);
    }
    acc[key.toLowerCase()] = val;
    return acc;
  }, {});
};

Works for nested object.