Getting backbone-rails to play nicely with iframe upload

backbone.iframe.sync.js

(function () {
  Backbone.syncWithoutUpload = Backbone.sync
  Backbone.syncWithUpload = function(method, model, options) {
	  var methodMap = {
	    'create': 'POST',
	    'update': 'PUT',
	    'delete': 'DELETE',
	    'read'  : 'GET'
	  };
		var type = methodMap[method];
		

		// Create iframe
    var iframe_id = 'file_upload_iframe_' + Date.now()
      , iframe = jQuery('<iframe id="' + iframe_id + '" name="' + iframe_id + '" ></iframe>').hide();

    // Create an hidden form
    var authToken = jQuery('meta[name=csrf-token]').attr('content')
      , authParam = jQuery('meta[name=csrf-param]').attr('content');
    
		// Find the form element based on the paramRoot.
		var form = $("#new-" + model.paramRoot);
		
		// Update the scope for all inputs.
		var inputs = form.find("input");
		_.each(inputs, function(el) {
			if ($(el).attr("name") != undefined){
				$(el).attr({
					'name': model.paramRoot + "[" + $(el).attr('name') + "]"
				})
			}
		});
		
		form.attr({
			'target':iframe_id,
			'action':model.url(),
			'method': type
		});
		if (form.has('input[name="'+ authParam +'"]').length == 0) {
			form.append('<input type="hidden" name="'+ authParam +'" value="'+ authToken +'" />');
		}
		form.append('<input type="hidden" name="is_iframe" value="true" />');
		
    jQuery(document.body).prepend(iframe);

    function callback() {
      // contentDocument doesn't work in IE (7)
			var iframe_body = (iframe[0].contentDocument || iframe[0].contentWindow.document).body;
			var response = JSON.parse(iframe_body.innerHTML);

      // TODO: Migrate to api v2. Make this check redundant
      response = response.objects ? response.objects : response;

      if (iframe_body.className !== "error") {
        var success = options.success
        if (success) options.success(response)
      } else {
        var error = options.error
        if (error) options.error(response)
      }

      iframe.remove();
      form.remove();
    }

    // Setup the iframe callback
    // for IE (7)
    iframe[0].onreadystatechange = function() {
      if (this.readyState === 'complete') {
        callback()
      }
    };

    // non-IE
    iframe[0].onload = callback;
    form[0].submit();
  }

  Backbone.sync = function(method, model, options) {
		if ( options && options.iframe ){
      Backbone.syncWithUpload(method, model, options)
    } else {
      Backbone.syncWithoutUpload(method, model, options)
    }
  };

}());