Generate Option tag string from ccomma-separated value.

index.html

<p>カンマ区切りで入力した値で option タグを生成。</p>
<textarea id="input-area" cols="30" rows="10"></textarea>

<button>Generate</button>

<div class="ret"></div>

<script>
// extract option list array from comma separated text
var extractArray = function() {
	var t = [];
  document.getElementById('input-area').value.split(',').forEach(function(e) {
    t.push(e.trim())
  });
  return t;
};

var generateOptionElements = function(list) {
	var parentElement = document.createElement('div');

	list.forEach(function(e) {
    var n = document.createElement('p');
    n.textContent = '<option value="' + e + '">' + e + '</option>';
    parentElement.appendChild(n);
  });
  
  return parentElement;
};

document.querySelector('button').addEventListener('click', function() {
	var t = extractArray();
  var retElm = document.querySelector('.ret');
  
  retElm.textContent = '';
  retElm.appendChild(generateOptionElements(t));
});
</script>