Post data with jquery ajax and overwrite/write file in external file

I have a problem with overwriting/writing file by sending data from an each function through jquery ajax. I think my post.php isn't correct can some help me with this feature?

$('.mod').each(function(){  
  var id = $(this).attr('id');

    $.ajax({
            type: "POST",
            url: "post.php",    
            data: "divid="+id+"&length="+$('.mod').length+"&ok=1",
            success: function(msg){  }
    });
 });

    if($_POST['ok']==1){        
                $File ='index.php';
    $Handle = fopen($File, 'w');
    $length = $_POST['length'] ;
    fwrite($Handle, ''.$_POST['divid'].'<br>');
    fcl开发者_JAVA百科ose($Handle); 
}

Regards Frank

---

serialize the data and send it to the php rather than doing each function

var ids = $("input[name='ids']").serializeArray();

like this just take the data into a variable and post it to php... not the whole form details only checkbox details