I trid to use an upload plugin for jQuery.
http://valums.com/ajax-upload/

When I set the returning respond type to json, firefox will popup a dialog asking how I like to handle the returning json object.

People have asked the same question at the upload script's author's page but no answer so far. Hopefully javascript guys here can figure out how we can handle this.

Thanks.

<script type= text/javascript>

      /*<![CDATA[*/

        $(document).ready(function(){



            /* example 1 */

            var button = $('#button1'), interval;

            new AjaxUpload(button, {

                //action: 'upload-test.php', // I disabled uploads in this example for security reasons

                action: '/posts/upload_images/', 

                name: 'myfile',

                responseType: 'json',

                onSubmit : function(file, ext){

                    // change button text, when user selects file           

                    button.text('Uploading');



                    // If you want to allow uploading only 1 file at time,

                    // you can disable upload button

                    this.disable();



                    // Uploding -> Uploading. -> Uploading...

                    interval = window.setInterval(function(){

                        var text = button.text();

                        if (text.length < 13){

                            button.text(text + '.');                    

                        } else {

                            button.text('Uploading');               

                        }

                    }, 200);

                },

                onComplete: function(file, response){

                    var json = response;

                    alert(json);

                    button.text('Upload');



                    window.clearInterval(interval);



                    // enable upload button

                    this.enable();



                    // add file to the list

//                    $('<li></li>').appendTo('#example1 .files').text(json.response_text);                     

                    $('<li></li>').appendTo('#example1 .files').text(file);                     

                }

            });

        });

    /*]]>*/

</script>