[bes]

<form id="form">
  <input type="checkbox"><br>
  <input type="checkbox"><br>
  <input type="checkbox"><br>
  <input type="checkbox"><br>
</form>

<script>
window.onload = function () {
  var form = document.getElementById('form');

  form.onclick = function (e)  {
    e = e || event;
    var target = e.target || e.srcElement;
    if (target.type == 'checkbox') {
      var next = target.nextSibling;
      if (next && next.tagName == 'DIV') {
        if (next.style.display == 'inline') {
          next.style.display = 'none';
        } else {
          next.style.display = 'inline';
        }
      } else {
        var div = document.createElement('div');  
        div.style.display = 'inline';
        div.innerHTML = '<input><span style="cursor: pointer" onclick="this.previousSibling.value=\'\'">&nbspx</span>';
        this.insertBefore(div, next);
      }
    }
  }

}
</script>