Java script ile listeden verileri cekme (getElementsByTagName)

<script type="text/javascript">


    function a() {
       
  
        var list = document.getElementsByTagName("LI");
    
        for (var i = 0; i < list.length; i++) {

            

            alert(list[i].firstChild.data);

        }
        document.getElementById("sayac").innerHTML = list.length;
    }


</script>

    <p id="sayac"></p>
<ul>

    <li> hasan aylas</li>

    <li> mustafa aylas</li>
    <li> hakkı aylas </li>



</ul>

  
<input id="buton" type="button" onclick="a()" value="Dene" />