<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
</head><body>
<form id="form1" name="form1" method="post" action="">
<label>
<input type="checkbox" id="cb1" name="checkbox" value="checkbox" />
</label>
</form>
<script language="javascript">
alert(document.getElementById("cb1").value);
</script>
</body>
</html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
</head><body>
<form id="form1" name="form1" method="post" action="">
<label>
<input type="checkbox" id="cb1" name="checkbox" value="checkbox" />
</label>
</form>
<script language="javascript">
alert(document.getElementById("cb1").value);
</script>
</body>
</html>
<tr>
<td><input type=checkbox value="333"></td>
</tr>
</table>
<script>
alert(tb.rows[0].cells[0].children[0].value)
</script>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
</head><body>
<form id="form1" name="form1" method="post" action="">
<label>
<input type="checkbox" id="cb1" name="checkbox" value="checkbox" />
</label>
</form>
<script language="javascript">
alert(document.getElementById("cb1").checked);
</script>
</body>
</html>