diff --git a/lib/cloudinary/__init__.py b/lib/cloudinary/__init__.py
index 7702ca9f..f9b79955 100644
--- a/lib/cloudinary/__init__.py
+++ b/lib/cloudinary/__init__.py
@@ -38,7 +38,7 @@ CL_BLANK = "data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAA
 URI_SCHEME = "cloudinary"
 API_VERSION = "v1_1"
 
-VERSION = "1.39.1"
+VERSION = "1.40.0"
 
 _USER_PLATFORM_DETAILS = "; ".join((platform(), "Python {}".format(python_version())))
 
diff --git a/lib/cloudinary/api.py b/lib/cloudinary/api.py
index cf5b2fca..0ae0fb33 100644
--- a/lib/cloudinary/api.py
+++ b/lib/cloudinary/api.py
@@ -565,7 +565,9 @@ def delete_folder(path, **options):
 
     :rtype: Response
     """
-    return call_api("delete", ["folders", path], {}, **options)
+
+    params = only(options, "skip_backup")
+    return call_api("delete", ["folders", path], params, **options)
 
 
 def restore(public_ids, **options):
diff --git a/lib/cloudinary/static/cloudinary/js/jquery.cloudinary.js b/lib/cloudinary/static/cloudinary/js/jquery.cloudinary.js
index 7b41a0f2..b61c442f 100644
--- a/lib/cloudinary/static/cloudinary/js/jquery.cloudinary.js
+++ b/lib/cloudinary/static/cloudinary/js/jquery.cloudinary.js
@@ -422,7 +422,7 @@ var slice = [].slice,
    * @returns {boolean} true if item is empty
    */
   isEmpty = function(item) {
-    return (item == null) || (jQuery.isArray(item) || Util.isString(item)) && item.length === 0 || (jQuery.isPlainObject(item) && jQuery.isEmptyObject(item));
+    return (item == null) || (Array.isArray(item) || Util.isString(item)) && item.length === 0 || (jQuery.isPlainObject(item) && jQuery.isEmptyObject(item));
   };
 
   /**
@@ -565,7 +565,7 @@ var slice = [].slice,
     setData: setData,
     width: width,
     isString: isString,
-    isArray: jQuery.isArray,
+    isArray: Array.isArray,
     isEmpty: isEmpty,
 
     /**
@@ -4728,7 +4728,7 @@ var slice = [].slice,
           return k + '=' + v;
         }).join('|');
       } else if (Util.isArray(value)) {
-        if (value.length > 0 && jQuery.isArray(value[0])) {
+        if (value.length > 0 && Array.isArray(value[0])) {
           upload_params[key] = jQuery.map(value, function(array_value) {
             return array_value.join(',');
           }).join('|');