digital_root

by wales

HTML

<div id="result">

</div>

JavaScript

function digital_root(n) {
  if (n >= 10) {
    var result = 0;
    var n_array = n.toString().split("");
    for (i = 0; i < n_array.length; i++) {
      result += parseInt(n_array[i]);
    }
    return digital_root(result);
  } else {
    document.getElementById("result").innerHTML = n;
    return n;
  }
}

document.getElementById("result").innerHTML = digital_root(16);