Looking at the source we can see that:
function baseForOwn(object, iteratee) {
return baseFor(object, iteratee, keys);
}
function baseForOwnRight(object, iteratee) {
return baseForRight(object, iteratee, keys);
}
function baseFor(object, iteratee, keysFunc) {
var index = -1,
iterable = toObject(object),
props = keysFunc(object),
length = props.length;
while (++index < length) {
var key = props[index];
if (iteratee(iterable[key], key, iterable) === false) {
break;
}
}
return object;
}
function baseForRight(object, iteratee, keysFunc) {
var iterable = toObject(object),
props = keysFunc(object),
length = props.length;
while (length--) {
var key = props[length];
if (iteratee(iterable[key], key, iterable) === false) {
break;
}
}
return object;
}
Both of the functions internally rely on keysFunc
, which returns the keys of the passed object. Since the order of an object's keys is not strictly defined the order cannot be known beforehand, however both of the methods internally use the same method, so the reversed order is guaranteed to be an exact reversal.