Given an index `n` and an array, return a new array with the nth value on the head

ascend.js

const clamp = l => h => x =>
  x > h
    ? h
    : x < l
      ? l
      : x

const
  ascend = i => xs => {
    let
      idx = clamp(0)(xs.length - 1)(i)
      
    return [
      xs[idx],
      ...xs.slice(0, idx),
      ...xs.slice(idx + 1),
    ]
  }

ascend(200)([1, 2, 3, 4, 5])

function ascend(head_index, list) {
  if (head_index < list.length && head_index >= 0) {
    var new_list = [];
    return new_list.concat(list[head_index], list.slice(0, head_index), list.slice(head_index + 1));
  }
}

Bem notado. Esqueci de checar se o índice é válido.

Edit: done