Cancel pending XHR when back/forward clicked

Author: AlexHill

jquery.pjax.js

@@ -408,6 +408,14 @@ if ('state' in window.history) {
 // You probably shouldn't use pjax on pages with other pushState
 // stuff yet.
 function onPjaxPopstate(event) {
+
+  // Cancel the current request if we're already pjaxing
+  var xhr = pjax.xhr
+  if ( xhr && xhr.readyState < 4) {
+    xhr.onreadystatechange = $.noop
+    xhr.abort()
+  }
+
   var state = event.state
 
   if (state && state.container) {