js获取单元格内容

<table width="100%" border="0" cellspacing="0" cellpadding="0" id="bg">
  <tr>
    <td>1-1</td>
    <td>1-2</td>
  </tr>
  <tr>
    <td>2-1</td>
    <td>2-2</td>
  </tr>
  <tr>
    <td>3-1</td>
    <td>3-2</td>
  </tr>
</table>

<script type="text/javascript">
var table = document.getElementById("bg");
for(var i=0;i<table.rows.length;i++)
{
	for(var j=0;j<table.rows[i].cells.length;j++)
	{
		alert(table.rows[i].cells[j].innerHTML);
	}
}
function getAllRowData(){
	var detailTable = document.getElementById("detailTable");
	for(var i = 1; i < table.rows.length; i++){
		var intCurrentRow = detailTable.rows[i].cells[8].innerHTML;
		var obj = getData(intCurrentRow);
		if(obj.id > 0){
			//更新
		}else {
			//添加
		}
	}
}
</script>