JavaScript动态创建表格与增加行数的实现

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>动态操作表格</title>
</head>
<body>
<script type="text/javascript">
var n = 0;
function showTable(len) 
{
 wi('<table border="1" width="300" style="border-collapse:collapse"><tbody id="table">');
 for (i=0;i<len;i++) 
 {
 if (parseInt(i%2)==1) 
{
  bg = '#F4FAC7';
 } 
else 
{
  bg = 'white'; 
 }
 wi('<tr bgcolor='+bg+'><td>第'+(i+1)+'行</td></tr>'); 
 }
 wi('</tbody></table><br />');
 wi('<input type="button" value="Add" id="add" />'); 
}</P>
<P>function wi(str) 
{
 return document.write(str); 
}
showTable(10);
var add = document.getElementById("add");
 add.onclick = function() {
 n = n+1;
 if (n%2==0) 
 {
 bg = '#F4FAC7';
 } 
 else 
 {
 bg = 'white'; 
 }
 var table = document.getElementById("table");
 var tr = document.createElement("tr");
 tr.bgColor = bg;
 var td = document.createElement("td");
 td.innerHTML = '第'+(10+n)+'行';
 tr.appendChild(td);
 table.appendChild(tr);
}
</script>
</body>
</html>