JS1：
function isTel(str){
var reg=/^([0-9]|[-])+$/g ;
if(str.length<7 || str.length>18){
return false;
}
else{
return reg.exec(str);
}
}
HTML：
<!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=utf-8" />
<title>无标题文档</title>
<script language="javascript">
function check(form){
if(form.name.vlaue==""){
alert("名字不能为空");
form.name.select();
return false();
}
}
</script>
</head>
<body>
<form id="form1" name="form1" method="post" action="">
<table width="100%" height="90" border="0" cellpadding="0" cellspacing="0">
<tr>
<td>姓名：
<label>
<input name="name" type="text" id="name" />
</label></td>
</tr>
<tr>
<td>电话：
<label>
<input name="tel" type="text" id="tel" />
</label></td>
</tr>
<tr>
<td><label>
<input type="submit" name="Submit" value="提交" />
</label></td>
</tr>
</table>
</form>
</body>
</html>