Why are you bringing reduce() into this? Seems to fly in the face of its common purpose, stated on the MDN page: Apply a function against an accumulator and each value of the array (from left-to-right) as to reduce it to a single value.
By doing it this way, you've introduced another symbol for us to consider (hash) and by departing from the standard for loop format, you've made it less idiomatic, which means more people will have to expend mental energy parsing it.
By doing it this way, you've introduced another symbol for us to consider (hash) and by departing from the standard for loop format, you've made it less idiomatic, which means more people will have to expend mental energy parsing it.