JS table 取特定值

function iteratorTable(tablename){
     var   total=0;
     for(var i=1;i<tablename.rows.length;i++)
     {   
        //取出第三列值的和
total+=parseFloat(tablename.rows[i].cells[2].innerText)
      }
      alert(total);
      }
   function test(){
     iteratorTable(document.getElementById("table"));
   }

<table id="table"  class="table">
<tr>
<th>NO</th>
<th>PRODUCT</th>
<th>PRICE</th>
</tr> 
<tr>
<th>1</th>
<th>smile</th>
<th>100</th>
</tr>
<tr>
<th>2</th>
<th>empty</th>
<th>20</th>
</tr>

</table>