diff --git a/src/jquery.form.js b/src/jquery.form.js
index 168d4b8b..579940dd 100644
--- a/src/jquery.form.js
+++ b/src/jquery.form.js
@@ -159,7 +159,7 @@
 		method = options.method || options.type || this.attr2('method');
 		action = options.url || this.attr2('action');
 
-		url = (typeof action === 'string') ? $.trim(action) : '';
+		url = (typeof action === 'string') ? action.trim() : '';
 		url = url || window.location.href || '';
 		if (url) {
 			// clean url (don't include hash vaue)
@@ -206,7 +206,7 @@
 		var qx, a = this.formToArray(options.semantic, elements, options.filtering);
 
 		if (options.data) {
-			var optionsData = $.isFunction(options.data) ? options.data(a) : options.data;
+			var optionsData = typeof options.data === 'function' ? options.data(a) : options.data;
 
 			options.extraData = optionsData;
 			qx = $.param(optionsData, traditional);
@@ -268,7 +268,7 @@
 			});
 
 		} else if (options.success) {
-			if ($.isArray(options.success)) {
+			if (Array.isArray(options.success)) {
 				$.merge(callbacks, options.success);
 			} else {
 				callbacks.push(options.success);
@@ -479,7 +479,7 @@
 				}
 
 			} else {
-				$io = $('<iframe name="' + id + '" src="' + s.iframeSrc + '" />', ownerDocument);
+				$io = $('<iframe name="' + id + '" src="' + s.iframeSrc + '" ></iframe>', ownerDocument);
 				$io.css({position: 'absolute', top: '-1000px', left: '-1000px'});
 			}
 			io = $io[0];
@@ -985,7 +985,7 @@
 		}
 
 		options = options || {};
-		options.delegation = options.delegation && $.isFunction($.fn.on);
+		options.delegation = options.delegation && typeof $.fn.on === 'function';
 
 		// in jQuery 1.3+ we can fix mistakes with the ready state
 		if (!options.delegation && this.length === 0) {
@@ -1123,7 +1123,7 @@
 			return a;
 		}
 
-		if ($.isFunction(filtering)) {
+		if (typeof filtering === 'function') {
 			els = $.map(els, filtering);
 		}