Write Number in Expanded Form

function expandedForm(num) {
  return String(num)
          .split("")
          .map((num, index, arr) => num + "0".repeat(arr.length - index -1 ))
          .filter((num) => Number(num) != 0)
          .join(" + ")
}

const expandedForm = n => n.toString()
                            .split("")
                            .reverse()
                            .map( (a, i) => a * Math.pow(10, i))
                            .filter(a => a > 0)
                            .reverse()
                            .join(" + ");