函数值已返回，但未在控制台中显示。说明？

Question

试着写一些小程序进行学习，第一次使用自调用函数。无法理解返回结果值的原因（正如我在Chrome Sources调试器中看到的那样），但未按预期在控制台中打印出来。

提前感谢您的解释。

function secondLowestAndHighest(numbers) {
  //an empty array for the result
  let result = new Array;
  //sorting out the array by ascending order with built-in method .sort()
  let lowToHigh = numbers.sort(function(a, b) {
    return a - b;
  });
  //reverse the array of numbers
  let highToLow = new Array;
  (function() {
    //self-invoked function, to call out automatically
    for (let i = lowToHigh.length - 1; i >= 0; i--) {
      highToLow.push(lowToHigh[i]);
    }
    return highToLow;
  })();

  result.push(lowToHigh[1], highToLow[1]);

  return result;
}

//secondLowestAndHighest([13, 105, 75, 1, 344, 6, 5]);
console.log(secondLowestAndHighest([13, 105, 75, 1, 344, 6, 5]))