closest-value-in-array.js

function closest(num, arr) {
  let idx = 0
  let curr = arr[idx]
  let diff = Math.abs(num - curr);
  for (var val = 0; val < arr.length; val++) {
    var newdiff = Math.abs(num - arr[val])
    if (newdiff < diff) {
      diff = newdiff
      curr = arr[val]
      idx = val
    }
  }
  return {
    value: curr,
    index: idx
  }
}