Accessing AJAX response

gistfile1.js

$(function() {

    function getFormData(cb){
      
      jQuery.ajax({
        type:'GET',
        url: 'http://localhost:3000/s3signature.json',
        error: function(jqXHR, textStatus, err){
            console.log('error!', textStatus);
            cb(err);
          },
        success: function(data){
          console.log('success!');
          cb(null, data);
        }
      })
    };
     
    // you cannot have the data here because getFormData() has not been called yet
    console.log("I want the data printed here: ");
    // here is where getFormData is called
    // you can print data by passing in a callback function
    console.log(getFormData(function(err, data) {
        console.log('was there an err?', err);
        console.log('here is the data', data);
    }));
    
    // I'm not quite sure what this has to do with the GET request?
    // this appears to simply upload a file to s3 
    $('#select-file').fileupload({
      maxFileSize: 100000000,
      fileInput:       $(this),
      url:             'https://ivancoffeetime.s3.amazonaws.com/',
      type:            'POST',
      autoUpload:       true,
      formData:         getFormData(),
      paramName:        'file', // S3 does not like nested name fields i.e. name="user[avatar_url]"
      dataType:         'XML',  // S3 returns XML if success_action_status is set to 201
      replaceFileInput: false,
      progressall: function (e, data) {
        var progress = parseInt(data.loaded / data.total * 100, 10);
        $("#progress-bar").css('width', progress + '%')
        console.log($("#progress-bar").css('width'));
      },
      start: function (e) {
        $("#progress-bar").css('background', 'green');
        $("#progress-bar").css('display', 'block');
        $("#progress-bar").css('width', '0%');
        $("#progress-bar").text('Loading file...');
      },
      done: function(e, data) {
       
        $("#progress-bar").text("Uploading done");

        // extract key and generate URL from response
        var key   = $(data.jqXHR.responseXML).find("Key").text();
        var url   = 'https://ivancoffeetime.s3.amazonaws.com/' + key;

        console.log("THIS IS THE URL: " + url);
        $("#thumbnail").html('<img src="'+url+'" style="width:100px;">');
      },
      fail: function(e, data) {
        // submitButton.prop('disabled', false);

        console.log(data);
        $("#progress-bar").
          css("background", "red").
          text("Failed");
      }
    });
    
  });