Array instance methods
.concat()
to return new merged Array
.fill()
to mutate array by fill with static value, from start (index) up to (not incl) end (index)
.flat()
to return new Array with sub-array elements moved up to optional depth
.slice()
Array Instance Method to return newshallow copy portion of Array
.reduce()
to return single acculated value from array after iterating over its elements