From 47095a7fa1551e771257408883d8e3f71a687ce1 Mon Sep 17 00:00:00 2001
From: Robin Ward <robin.ward@gmail.com>
Date: Tue, 11 Jun 2019 11:50:11 -0400
Subject: [PATCH] FIX: Memory leak when adding ajax prefilter repeatedly.

---
 .../discourse/initializers/csrf-token.js.es6  | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/app/assets/javascripts/discourse/initializers/csrf-token.js.es6 b/app/assets/javascripts/discourse/initializers/csrf-token.js.es6
index fd95c274d96..0ddd5dda5d5 100644
--- a/app/assets/javascripts/discourse/initializers/csrf-token.js.es6
+++ b/app/assets/javascripts/discourse/initializers/csrf-token.js.es6
@@ -1,16 +1,21 @@
 //  Append our CSRF token to AJAX requests when necessary.
+
+let installedFilter = false;
+
 export default {
   name: "csrf-token",
   initialize: function(container) {
-    var session = container.lookup("session:main");
-
     // Add a CSRF token to all AJAX requests
+    let session = container.lookup("session:main");
     session.set("csrfToken", $("meta[name=csrf-token]").attr("content"));
 
-    $.ajaxPrefilter(function(options, originalOptions, xhr) {
-      if (!options.crossDomain) {
-        xhr.setRequestHeader("X-CSRF-Token", session.get("csrfToken"));
-      }
-    });
+    if (!installedFilter) {
+      $.ajaxPrefilter(function(options, originalOptions, xhr) {
+        if (!options.crossDomain) {
+          xhr.setRequestHeader("X-CSRF-Token", session.get("csrfToken"));
+        }
+      });
+      installedFilter = true;
+    }
   }
 };