js 动态增加表格

function insRow(){

    document.getElementById("rowId").value=parseInt(document.getElementById("rowId").value)+1;

    var rowId = document.getElementById("rowId").value;

    var tb1 = document.getElementById("ctable");

function insRow(){
		
	document.getElementById("rowId").value=parseInt(document.getElementById("rowId").value)+1;
		
	var rowId = document.getElementById("rowId").value;

	var tb1 = document.getElementById("ctable"); 

<span style="color: rgb(255, 0, 0);">var rowsCount=tb1.rows.length;</span>

	var rowsCount=tb1.rows.length;

<span style="color: rgb(255, 0, 0);">
    var row = tb1.insertRow(rowsCount);   </span>

	var row = tb1.insertRow(rowsCount);   

<span style="color: rgb(255, 0, 0);">
    var cell = row.insertCell(0);  </span>
    cell.innerHTML="<img src=\"<%=contextPath%>/img/update.gif\" class=\"nav\" />";
     var cell = row.insertCell(1);
    cell.innerHTML="<input name=\"companyname"+rowId+"\" ID=\"companyname"+rowId+"\" type=\"text\" />";
    var cell = row.insertCell(2);
    cell.innerHTML="<input name=\"companynameen"+rowId+"\" ID=\"companynameen"+rowId+"\" type=\"text\"  />";
}