js using recursion to create a range of numbers

CSS

* {
  box-sizing: border-box;
  transition: all 0.2s;
  scroll-behavior: smooth;
}

JS

/***************************************/
        Not Finished - 25.11.19
/***************************************/

function run_function() {
  var my_result = "A Result";
  write_result(my_result);
  return my_result;
}

function rangeOfNumbers(startNum, endNum) {
  if(endNum === startNum) {
    return [endNum];
  } else {
    var numbers = rangeOfNumbers(startNum - 1);
    numbers.push(startNum);
    return numbers;
  }
};

// this is a common function just to write the content into the result div
function write_result(result) {
  var result_html = document.getElementById("result");
  result_html.innerHTML = result;
}

HTML

<div id='result' class='mb-3 alert alert-primary'>..</div>
<button onclick='run_function();' class='btn btn-primary mb-1'>Run Function</button>

Working Result

Test Result Below