From e403bd9f9383686fb7b681532386b009f2ee853b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roman=20Smr=C5=BE?= <roman.smrz@seznam.cz>
Date: Thu, 27 Mar 2025 20:14:41 +0100
Subject: Generate sample interactive page

---
 src/Main.hs | 51 +++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 49 insertions(+), 2 deletions(-)

(limited to 'src')

diff --git a/src/Main.hs b/src/Main.hs
index 65ae4a0..69276ac 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -1,4 +1,51 @@
-module Main where
+module Main (main, setup) where
+
+import GHC.Wasm.Prim
 
 main :: IO ()
-main = putStrLn "Hello, Haskell!"
+main = error "unused"
+
+foreign export javascript setup :: IO ()
+setup :: IO ()
+setup = do
+    body <- js_document_getElementById (toJSString "body")
+    js_set_innerHTML body (toJSString "<input id=\"some_input\" type=\"text\" value=\"xyz\" /><button id=\"some_button\">add</button></div><div><ul id=\"some_list\"></ul></div>")
+
+    buttonElem <- js_document_getElementById (toJSString "some_button")
+    buttonCallback <- asEventListener onButtonClick
+
+    js_addEventListener buttonElem (toJSString "click") buttonCallback
+
+onButtonClick :: JSVal -> IO ()
+onButtonClick _event = do
+    inputElem <- js_document_getElementById (toJSString "some_input")
+    listElem <- js_document_getElementById (toJSString "some_list")
+
+    li <- js_document_createElement (toJSString "li")
+    content <- js_document_createTextNode =<< js_get_value inputElem
+    js_appendChild li content
+    js_appendChild listElem li
+
+foreign import javascript unsafe "document.getElementById($1)"
+    js_document_getElementById :: JSString -> IO JSVal
+
+foreign import javascript unsafe "$1.innerHTML = $2"
+    js_set_innerHTML :: JSVal -> JSString -> IO ()
+
+foreign import javascript unsafe "$1.appendChild($2)"
+    js_appendChild :: JSVal -> JSVal -> IO ()
+
+foreign import javascript unsafe "document.createElement($1)"
+    js_document_createElement :: JSString -> IO JSVal
+
+foreign import javascript unsafe "document.createTextNode($1)"
+    js_document_createTextNode :: JSString -> IO JSVal
+
+foreign import javascript unsafe "$1.value"
+    js_get_value :: JSVal -> IO JSString
+
+foreign import javascript unsafe "$1.addEventListener($2, $3)"
+    js_addEventListener :: JSVal -> JSString -> JSVal -> IO ()
+
+foreign import javascript "wrapper"
+    asEventListener :: (JSVal -> IO ()) -> IO JSVal
-- 
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