在开发模式下使用Rails 3.2处理请求的顺序

Question

I have a page that displays a spinner animation while dynamic content is loaded asynchronously (HAML here):

#loading_spinner

#async_vote

:javascript    
  $(document).ready(function() {
    $.ajax({
      url: "/votes/voteables",
      cache: false,
      beforeSend: function(xhr){
        $("#loading_spinner").show();
      },
      success: function(html){
        $("#loading_spinner").hide();
        $("#async_vote").html(html);
      }
    });
  });

To simulate a slow request, I have put a sleep of a few seconds into the :voteables -method.

Now, the problem is that the browser does not show the background-image of the #loading_spinner -element.

What happens is that although the JavaScript-code should execute when the page is loaded, it actually executes the AJAX-call before it fetches the background-image for the spinner. So when the delay in the controller is 3 seconds, the image is loaded immediately afterwards (because the requests are not served in parallel), the success -callback is executed and the image is immediately hidden.

I am using Rails 3.2 and running the app with rails server .

Any recommendations how to fix this issue in development? And will it be an issue in production?

Answer 1

I think if you wrap the ajax request in load, instead of ready, it won't execute until the images have downloaded, like this:

$(window).load(function(){
  // ajax functionality goes here
});