From f3942ae7724ff92d1949f245ddc1cb37c3dba9c8 Mon Sep 17 00:00:00 2001
From: Jean-Paul Calderone <exarkun@twistedmatrix.com>
Date: Tue, 25 Apr 2023 08:36:42 -0400
Subject: [PATCH] some explainers
---
obelisk/frontend/src/Pages/TechDemo.hs | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/obelisk/frontend/src/Pages/TechDemo.hs b/obelisk/frontend/src/Pages/TechDemo.hs
index 77e48b0..d565609 100644
--- a/obelisk/frontend/src/Pages/TechDemo.hs
+++ b/obelisk/frontend/src/Pages/TechDemo.hs
@@ -119,9 +119,17 @@ techDemoPage = prerender_ (pure ()) $ do
-- | Render a "Back" button hooked up to the browser history navigation action "back".
navigationDemo :: (Prerender t m, DomBuilder t m) => m ()
navigationDemo = do
+ -- This renders a button into the page so there is something to see and
+ -- click on. It returns an `Event t ()` that triggers when the button is
+ -- clicked.
backEv <- button "Back"
- prerender_ blank $ do
- -- performEvent_? Why?
+
+ -- Only do the rest of this on the client. There's no way to look up the
+ -- browser Window or History when doing server-side rendering.
+ prerender_ blank $
+
+ -- Use performEvent_ to take an action on the Window whenever the event
+ -- triggers.
performEvent_ . ffor backEv $ \() -> do
windowM <- currentWindow
case windowM of
--
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