Get the index of the minimum number in the array. For 2nd one, reduce replaces python's min w/ a key since we don't have that in js.

indexOfMin.js

const indexOfMin = numbers => {
  return numbers.indexOf(Math.min(...numbers))
}

indexOfMinOnePassThrough.js

const indexOfMin = numbers => {
  if(!numbers.length) return -1
  return numbers.reduce((minI, curr, i) => curr < numbers[minI] ? i : minI, 0)
}