Deep Sort Javascript Object

sort.js

function sortObject(object) {
  //Thanks > http://whitfin.io/sorting-object-recursively-node-jsjavascript/
  if (!object) {
    return object;
  }

  const isArray = object instanceof Array;
  var sortedObj = {};
  if (isArray) {
    sortedObj = object.map((item) => sortObject(item));
  } else {
    var keys = Object.keys(object);
    // console.log(keys);
    keys.sort(function(key1, key2) {
      (key1 = key1.toLowerCase()), (key2 = key2.toLowerCase());
      if (key1 < key2) return -1;
      if (key1 > key2) return 1;
      return 0;
    });

    for (var index in keys) {
      var key = keys[index];
      if (typeof object[key] == 'object') {
        sortedObj[key] = sortObject(object[key]);
      } else {
        sortedObj[key] = object[key];
      }
    }
  }

  return sortedObj;
}