[bes]

<form  method=get action="#" name="chekcms">
  <input type=checkbox name="wordpress">wordpress<br>
  <input type=checkbox name="ucoz">ucoz<br>
  <input type=checkbox name="dle">dle<br>
</form>

<button id="myBut">click</button>

<script>
myBut.onclick = function () {
	var inp = document.getElementsByTagName('input');
	var length = inp.length;
	var mas = [];

	for (var i = 0; i < length; i++) {
		mas.push(inp[i].nextSibling.textContent);//nodeValue, data
	}
	alert(mas.join(','));

}
</script>