how to return value from ajax

hello

i want 2 return true/false return from Ajax function

function valid(){
if(document.frm1.name.value==""){
document.frm1.name .focus();
alert("Please enter name");
return false;
}

 [COLOR="Red"]check_present_user(url,"GET","message_div");[/COLOR]

/ how to get return value & check/

if(document.frm1.address.value==""){
    document.frm1.address.focus();
    alert("Please enter address");
    return false; 
 }

return true;
}

function submitForm(){
if(valid()==true){
document.frm1.submit();
}
}

pls help me

thank you

This post is handled at another forum.