Find non-seqesential numbers in an array

by Gshegosh

HTML

<h2>for loop method for finding non-sequential slots (holes) in an array</h2>
    <p id="demo"></p>

JavaScript

const numbers = [1, 2, 3, 4, 6, 7];

document.getElementById("demo").innerHTML = numbers;
let hole;

holeFinder()

function holeFinder() {
  for (let i = 0; i < numbers.length; i++) {
    if (numbers[0] > 1) {
      /*  console.log(numbers[0]) */
      hole = 1;
      document.getElementById("demo").innerHTML += "<br>1: hole: " + hole;
      return hole;
    }

    if (numbers[i] > 1) {
      if ((numbers[i] - numbers[i - 1]) > 1) {
        hole = (numbers[i - 1] + 1)
        document.getElementById("demo").innerHTML += "<br>2: hole: " + hole;
        return hole;
      }

      if ((numbers[i] - numbers[i - 1]) == 1) {
        hole = numbers[numbers.length - 1] + 1;
        document.getElementById("demo").innerHTML += "<br>3: hole: " + hole;
        return hole;
      }
    }
  }
}