SO34215091 clear form fields

HTML

<script>
  function ClearFormElements(formId) {
    var nElements = document[formId].elements.length;
    for (var i = 0; i < nElements; i++) {

      if (document[formId].elements[i].type === "checkbox") {
        document[formId].elements[i].checked = false;
      }

    }
  }

</script>
<div>
  <form name="PopulateModemALL" ID="PopulateModemALL" action="populate_modemALL">
    <input type="checkbox" name="cbA" value="yes" checked>
    <label for="cbA">Checkbox</label>
  </form>
  <input ID="ModemAllTableClear" class="ButtonTables_Clear" type="button" value="Clear" name="clear_ModemALLTable" onclick="ClearFormElements('PopulateModemALL')" />
</div>