Function reduce

reduce(reducer, accumulator): any
Create a new Set with elements that are filtered and transformed by a provided reducer function.
Parameters
- reducer: ((arg0, arg1, arg2, arg3) => any)
  A reducer function applied to each value. Positional arguments are the accumulator, the value, the index of iteration, and the set being reduced.
  - - (arg0, arg1, arg2, arg3): any
    - Parameters
      arg0: any
      arg1: any
      arg2: number
      arg3: Set<any>
      Returns any
- accumulator: any
  The initial value of the returned accumulator.
Returns any
The final value of the accumulator.

See
Array#reduce