如何通过jquery发送变量

I just created an autocomplete textbox via jquery now i am stuck with two problems.

1) I need to get the value of the selected item from the Autocomplete list.

So far i did these..

My jquery

$(document).ready(function(){
$("#tag").autocomplete("autocomplete.php", {
    selectFirst: true

});
});

I am getting the autocomplete list from the database its working fine, but the problem is that

2) When i type 'r' all the names with values gets populated and if i select say Robin from the list and try to display it with alert, i only gets 'r', (i only typed r,and selected 'robin' from list) why is this so?

here is the code i wrote for this

for the autocomplete textbox

  <input name="tags" type="text" id="tag"  value="" onchange= "newfn()" />

and in newfn()

<script>
        function newfn()
        {

             authname = document.getElementById("tag").value;

            document.autoquote.qid.value=authname;
            alert(authname);

        }
    </script>

and if i put an alert at first saying

alert("Hi");

then, i get first alert saying hi, and I get robin not r

So what is the correct way to get what value i selected from the autocomplete list?

Now my second Question is that the selected value from this autocomplete textbox, I need to pass it with another jquery to another php page so that I can get this value there and give it in a query as a criteria.

you can use the autocomplete's select property like this

$("#tag").autocomplete('autocomplete.php', {
    selectFirst: true,
    select: function (event, ui) {
        var label = ui.item.label;
        var value = ui.item.value;
        alert(label);
        alert(value)
     // you can write additional javascript code here to make use of these values

    }
 });

Please check the jQuery UI documentation for more examples and info.

Here is a JSFiddle.(Please note that an additional source attribute has been added in the fiddle to simulate the loading of data set as real cross domain AJAX calls are not allowed)

Because it is not the way to catch a select event http://api.jqueryui.com/autocomplete/#event-select :

$(document).ready(function(){
    $("#tag").autocomplete("autocomplete.php", {
        selectFirst: true,
        select: function( event, ui ) {
            //Then use "ui" object, for example ui.item.label or ui.item.value                
        }
    });
});

$(".autosearch-smart").autocomplete('autocomplete.php', {
 select: function( event, ui ) {
    // here you can get id and values from the autocomplete list
   // try to debug
     console.log(ui.item.id);
     console.log(ui.item.label);
     console.log(ui.item.value);
}


});

$(document).ready(function(){
$("#tag").autocomplete("autocomplete.php", {
    selectFirst: true
    select: function( event, ui ) {
         //check the values in console    
         alert(ui.item.value+" - "+ui.item.value);      
    }
});
});