Wt

I have a single page application using internal paths and SAML for authentication. The SAML authentication works great and end up at my landing page as expected. When I click on a sub-page everything works fine. But when I navigate back, the page doesn't change.

I get this error in the JavaScript console when navigating back:

?wtd=Nn8DKBBvIyRPDLeg&sid=1074320452&scrW=1920&scrH=1200&tz=-480&tzS=America%2FLos_Angeles&htmlHistory=true&deployPath=%2F&request=script&rand=2159790336:18  Uncaught TypeError: Cannot read properties of undefined (reading 'length')
    at onHashChange (?wtd=Nn8DKBBvIyRPDLeg&sid=1074320452&scrW=1920&scrH=1200&tz=-480&tzS=America%2FLos_Angeles&htmlHistory=true&deployPath=%2F&request=script&rand=2159790336:18:13615)
    at ?wtd=Nn8DKBBvIyRPDLeg&sid=1074320452&scrW=1920&scrH=1200&tz=-480&tzS=America%2FLos_Angeles&htmlHistory=true&deployPath=%2F&request=script&rand=2159790336:18:12119
onHashChange @ ?wtd=Nn8DKBBvIyRPDLeg&sid=1074320452&scrW=1920&scrH=1200&tz=-480&tzS=America%2FLos_Angeles&htmlHistory=true&deployPath=%2F&request=script&rand=2159790336:18
(anonymous) @ ?wtd=Nn8DKBBvIyRPDLeg&sid=1074320452&scrW=1920&scrH=1200&tz=-480&tzS=America%2FLos_Angeles&htmlHistory=true&deployPath=%2F&request=script&rand=2159790336:18

This is where the error comes from:

In this situation, e, or rather history's current state, is undefined.

It appears that, in JavaScript, null !== is not sufficient to check for undefined. I didn't dig into it much, but I see null !== used in quite a few places in Wt, so I assume history's current state is supposed to be assigned somewhere but SAML messes with that assignment. I do not see this problem if I disable SAML. I also do not see this problem if I use a link to go back to the landing page, then click on a sub-page and navigate back. It appears that by that point history's current state is sufficiently initialized.

My current fix for this is to use null !=, which checks for null and undefined in JavaScript:

diff --git a/src/web/skeleton/Wt.js b/src/web/skeleton/Wt.js
index 817742e..b2ed40b 100644
--- a/src/web/skeleton/Wt.js
+++ b/src/web/skeleton/Wt.js
@@ -2289,7 +2289,7 @@ window._$_APP_CLASS_$_ = new (function() {
     const newLocation = _$_WT_CLASS_$_.history.getCurrentState();

     if (
-      newLocation !== null &&
+      newLocation != null &&
       newLocation.length > 0 &&
       !newLocation.startsWith("/")
     ) {

I don't feel like this is the correct long-term solution, but it works for now.

I'm using Wt version 4.11.0.