function TiJiao(form_name,title_name,show_error)
{
//在这里你需要找到form_name的对象
var form = document.getElementsByName(form_name)[0];
if (Trim(form.title_name.value)=='')
{
alert(show_error);
form_name.title_name.focus();
return false;
}
}

------解决方案--------------------

HTML code

<script>
function Trim(str){
var rtnStr;
rtnStr=""
for (var i=0;i<str.length;i++){
if (str.charAt(i)!=" "){
rtnStr=str.substr(i);
break;
}
}
return rtnStr;
}

function TiJiao(form1,i,show_error)
{
if (Trim(form1.elements[i].value)=='')
{
alert(show_error);
form1.elements[i].focus();
return false;
}
}


function check(tt1)
{
tt=document.getElementById(tt1);
TiJiao(tt,0,'请输入名称');
TiJiao(tt,1,"请输入密码");
}
</script>


<FORM name="form1" method="post" action="" id="form1" onSubmit="return check('form1')">
<input type="text" name="acc' id="acc" />
<input type="text" name="psd' id="psd" />
<input type="submit" name="btsub' id="btsub" value="submit"/>
</FORM>