sub check
if frm1.zh.value=empty then
alert"帐号不能为空，请输入帐号!"
focusto(0)
exit sub
end if
if frm1.mm.value=empty then
alert"密码不能为空，请输入密码!"
focusto(1)
exit sub
end if
end sub

sub focusto(x)
document.frm1.elements(x).focus()
end sub