Array Flat

array.flatten.ts

type TupleRecursive<T> = T | Tuple<T>

export type Tuple<T> = TupleRecursive<T>[]

const isArray = Array.isArray

export const flat = <T>(tuple: Tuple<T>): T[] => {
  const result: T[] = []

  const flatten = (tuple: Tuple<T>): void => {
    tuple.forEach(item => {
      if (isArray(item)) {
        flatten(item)
      } else {
        result.push(item)
      }
    })
  }
  
  if (isArray(tuple)) {
    flatten(tuple)
  }

  return result
}