improve task list handling

assets/page/actions.js

@@ -3,6 +3,36 @@ function encodePickedPath(p) {
     return '/' + p.replace(/^\/+/, '').split('/').map(encodeURIComponent).join('/');
 }
 
+// postReplace POSTs to action with the optional form body, then loads target
+// into the current history entry — so the action and its result occupy one
+// entry instead of two, and back-navigation skips past the stale pre-mutation
+// snapshot in bfcache. body may be null for empty POSTs.
+//
+// We can't just call window.location.replace(target): when target differs from
+// the current URL only by fragment, the browser updates the URL bar without
+// re-fetching, so a server-side mutation wouldn't be reflected. Instead,
+// rewrite the current entry's URL via history.replaceState, then reload — the
+// reload always re-fetches and preserves the (new) URL including its fragment.
+function postReplace(action, body, target) {
+    var init = { method: 'POST', redirect: 'manual' };
+    if (body) {
+        init.headers = { 'Content-Type': 'application/x-www-form-urlencoded' };
+        init.body = body;
+    }
+    fetch(action, init).then(function (res) {
+        if (res.type === 'opaqueredirect' || res.ok) {
+            window.history.replaceState(null, '', target);
+            window.location.reload();
+            return;
+        }
+        return res.text().then(function (msg) {
+            alert(msg || ('Request failed (' + res.status + ')'));
+        });
+    }).catch(function () {
+        alert('Network error');
+    });
+}
+
 function promptPageName(title, initial, confirmLabel, onName) {
     var input = document.createElement('input');
     input.type = 'text';
@@ -89,11 +119,9 @@ function movePage() {
                         var action = window.location.pathname + '?move=' +
                             encodeURIComponent(dest);
                         if (linksCheckbox.checked) action += '&links=1';
-                        var form = document.createElement('form');
-                        form.method = 'POST';
-                        form.action = action;
-                        document.body.appendChild(form);
-                        form.submit();
+                        var target = encodePickedPath(dest) + '/';
+                        closeModal();
+                        postReplace(action, null, target);
                     }
                 }
             });
@@ -112,11 +140,11 @@ function deletePage() {
             danger: true,
             enterConfirms: false,
             onConfirm: function () {
-                var form = document.createElement('form');
-                form.method = 'POST';
-                form.action = window.location.pathname + '?delete=1';
-                document.body.appendChild(form);
-                form.submit();
+                var p = window.location.pathname.replace(/\/+$/, '');
+                var idx = p.lastIndexOf('/');
+                var parent = idx > 0 ? p.substring(0, idx + 1) : '/';
+                closeModal();
+                postReplace(window.location.pathname + '?delete=1', null, parent);
             }
         },
         cancel: { autofocus: true },