怎么用java脚本验证？

Question

http://expert.csdn.net/Expert/TopicView3.asp?id=2292447

Answer 1

<script language="JavaScript">
function check_input()
{
  newuserreg=document.form1;
         if(newuserreg.txtnum.value=="")
            {
              alert("编号不能为空");
              newuserreg.txtnum.focus();
              return false;
             }   
  //判断编号是否为数字
if(newuserreg.txtnum.value!='')
{
   var newvalue=newuserreg.txtnum.value;
   var newlength=newvalue.length;
   for(var i=0;i!=newlength;i++)   
      {
      achar=newvalue.substring(i,i+1);
      if(achar<"0"||achar>"9")
      {
      alert('学号请输入数字');
      newuserreg.txtnum.focus();
      return false;
      }
      } 
 }  
//判断编号位数  
 newuserreg=document.form1;
 if(newuserreg.txtnum.value.length>5)
{
alert("学号应该小于5位");
newuserreg.txtnum.focus();
return false;
}  
         newuserreg=document.form1;
         if(newuserreg.txtname.value=="")
            {
              alert("姓名不能为空");
              newuserreg.txtname.focus();
              return false;
             }  doucment.all.form1.submit();
}          
</script>