web: scroll to top on page changes

web/src/state.rs

@@ -59,13 +59,20 @@ pub fn init(url: Url, orders: &mut impl Orders<Msg>) -> Model {
 
 fn on_url_changed(uc: subs::UrlChanged) -> Msg {
     let mut url = uc.0;
+    let href = document().location().unwrap().href().unwrap();
+    let origin = document().location().unwrap().origin().unwrap();
+    let current_url = &href[origin.len()..];
+    let did_change = current_url != url.to_string();
+    let mut messages = Vec::new();
+    if did_change {
+        messages.push(Msg::ScrollToTop)
+    }
     info!(
-        "url changed '{}', history {}",
-        url,
+        "url changed\nold '{current_url}'\nnew '{url}', history {}",
         history().length().unwrap_or(0)
     );
     let hpp = url.remaining_hash_path_parts();
-    match hpp.as_slice() {
+    let msg = match hpp.as_slice() {
         ["t", tid] => Msg::ShowThreadRequest {
             thread_id: tid.to_string(),
         },
@@ -102,7 +109,9 @@ fn on_url_changed(uc: subs::UrlChanged) -> Msg {
                 last: None,
             }
         }
-    }
+    };
+    messages.push(msg);
+    Msg::MultiMsg(messages)
 }
 
 // `update` describes how to handle each `Msg`.
@@ -536,6 +545,10 @@ pub fn update(msg: Msg, model: &mut Model, orders: &mut impl Orders<Msg>) {
                     .expect("failed to copy to clipboard");
             });
         }
+        Msg::ScrollToTop => {
+            info!("scrolling to the top");
+            web_sys::window().unwrap().scroll_to_with_x_and_y(0., 0.);
+        }
         Msg::WindowScrolled => {
             if let Some(el) = model.content_el.get() {
                 let ih = window()
@@ -608,6 +621,7 @@ pub fn update(msg: Msg, model: &mut Model, orders: &mut impl Orders<Msg>) {
             orders.send_msg(Msg::CatchupNext);
         }
         Msg::CatchupNext => {
+            orders.send_msg(Msg::ScrollToTop);
             let Some(catchup) = &mut model.catchup else {
                 orders.send_msg(Msg::GoToSearchResults);
                 return;
@@ -777,6 +791,7 @@ pub enum Msg {
 
     CopyToClipboard(String),
 
+    ScrollToTop,
     WindowScrolled,
     SetProgress(f64),
     UpdateServerVersion(String),