auto reload at file change

main.py

@@ -1,7 +1,8 @@
 import os
-from flask import Flask
-from watchdog.observers import Observer
+from flask import Flask, Response
+import threading
 from watchdog.events import FileSystemEventHandler
+from watchdog.observers import Observer
 
 # --------------  VARIABLES   --------------
 html_file_path = r"PATH"
@@ -12,20 +13,27 @@ scroll_pixels = 100
 scroll_interval = 3  # seconds
 bottom_wait_time = 3  # seconds
 top_wait_time = 3  # seconds
-reload_interval = 35  # seconds
 # -------------- END VARIABLES --------------
 
 app = Flask(__name__)
+file_change_event = threading.Event()
 
 
 class FileChangeHandler(FileSystemEventHandler):
-    def __init__(self, app):
-        self.app = app
-
     def on_modified(self, event):
         if event.src_path == html_file_path:
-            with self.app.app_context():
-                self.app.config["TEMPLATES_AUTO_RELOAD"] = True
+            file_change_event.set()
+
+
+@app.route("/_file_change")
+def file_change_stream():
+    def stream():
+        while True:
+            file_change_event.wait()
+            yield "data: reload\n\n"
+            file_change_event.clear()
+
+    return Response(stream(), content_type="text/event-stream")
 
 
 @app.route("/")
@@ -38,12 +46,11 @@ def serve_html():
             scroll-behavior: smooth;
         }}
     </style>
-    <script>
+<script>
         let scrollAmount = {scroll_pixels};
         let scrollInterval = {scroll_interval} * 1000;
         let bottomWaitTime = {bottom_wait_time} * 1000;
         let topWaitTime = {top_wait_time} * 1000;
-        let reloadInterval = {reload_interval} * 1000;
         let scrollPos = 0;
         let scrollingDown = true;
 
@@ -76,7 +83,10 @@ def serve_html():
         window.onload = function() {{
             window.scrollTo(0, 0);
             if (document.body.scrollHeight <= window.innerHeight) {{
-                setTimeout(reloadPage, reloadInterval);
+                const eventSource = new EventSource('/_file_change');
+                eventSource.onmessage = function() {{
+                    location.reload();
+                }};
             }} else {{
                 setTimeout(autoScroll, topWaitTime);
             }}
@@ -87,7 +97,7 @@ def serve_html():
 
 
 if __name__ == "__main__":
-    event_handler = FileChangeHandler(app)
+    event_handler = FileChangeHandler()
     observer = Observer()
     observer.schedule(
         event_handler, path=os.path.dirname(html_file_path), recursive=False
@@ -97,4 +107,4 @@ if __name__ == "__main__":
         app.run(host=host, port=port)
     except KeyboardInterrupt:
         observer.stop()
-    observer.join()
+    observer.join()