Question

I was wondering how to take a value from a ajax call and change the value of a textfield to that value.

I have the following call which grabs the users id and displays an alert box with that value, instead of displaying an alert box, i would like to change the value of a textbox to display that value in it .. any help would be grand.

<script type="text/javascript" charset="utf-8">
$('#users').live('change', function(){

    $.ajax({
        type: "POST",
        url: "returndata",
        data: {id: $(':selected', this).val()},
        dataType: 'json',
        success: function(data){
            alert(data.id);
        }
    });
});                     
</script>

Answer 1

Just change your success function to alter the value of the textfield instead of performing the alert

Suppose the textfield in question has id="textFieldId"

    success: function(data){ 
                 $("#textFieldId").val(data.id);
                 //$("#textFieldId").text(data.id);  im not sure if you need .val or .text   what kind of element is this textfield?
                }

You can probably simplify this, if you care to, with $.load() instead of $.ajax(). http://api.jquery.com/load/