fix: stale placeholder decorations on empty paragraphs (#2374)

apps/client/src/features/editor/extensions/extensions.ts

@@ -3,7 +3,8 @@ import { StarterKit } from "@tiptap/starter-kit";
 import { Code } from "@tiptap/extension-code";
 import { TextAlign } from "@tiptap/extension-text-align";
 import { TaskList, TaskItem } from "@tiptap/extension-list";
-import { Placeholder, CharacterCount, UndoRedo } from "@tiptap/extensions";
+import { CharacterCount, UndoRedo } from "@tiptap/extensions";
+import { Placeholder } from "@/features/editor/extensions/placeholder";
 import { Superscript } from "@tiptap/extension-superscript";
 import SubScript from "@tiptap/extension-subscript";
 import { Typography } from "@tiptap/extension-typography";

apps/client/src/features/editor/extensions/placeholder.ts

@@ -0,0 +1,64 @@
+import { isNodeEmpty } from "@tiptap/core";
+import { Plugin, PluginKey } from "@tiptap/pm/state";
+import { Decoration, DecorationSet } from "@tiptap/pm/view";
+import { Placeholder as TiptapPlaceholder } from "@tiptap/extensions";
+
+export const Placeholder = TiptapPlaceholder.extend({
+  addProseMirrorPlugins() {
+    const editor = this.editor;
+    const options = this.options;
+    const dataAttribute = `data-${options.dataAttribute || "placeholder"}`;
+
+    return [
+      new Plugin({
+        key: new PluginKey("docmostPlaceholder"),
+        props: {
+          decorations: (state) => {
+            if (options.showOnlyWhenEditable && !editor.isEditable) {
+              return null;
+            }
+
+            const { doc, selection } = state;
+            const { anchor } = selection;
+            const decorations: Decoration[] = [];
+            const isEmptyDoc = editor.isEmpty;
+
+            doc.descendants((node, pos) => {
+              if (!node.type.isTextblock) {
+                return options.includeChildren;
+              }
+
+              const hasAnchor = anchor >= pos && anchor <= pos + node.nodeSize;
+              const isEmpty = !node.isLeaf && isNodeEmpty(node);
+
+              if ((hasAnchor || !options.showOnlyCurrent) && isEmpty) {
+                const emptyNodeClass =
+                  typeof options.emptyNodeClass === "function"
+                    ? options.emptyNodeClass({ editor, node, pos, hasAnchor })
+                    : options.emptyNodeClass;
+                const classes = [emptyNodeClass];
+                if (isEmptyDoc) {
+                  classes.push(options.emptyEditorClass);
+                }
+
+                decorations.push(
+                  Decoration.node(pos, pos + node.nodeSize, {
+                    class: classes.join(" "),
+                    [dataAttribute]:
+                      typeof options.placeholder === "function"
+                        ? options.placeholder({ editor, node, pos, hasAnchor })
+                        : options.placeholder,
+                  }),
+                );
+              }
+
+              return options.includeChildren;
+            });
+
+            return DecorationSet.create(doc, decorations);
+          },
+        },
+      }),
+    ];
+  },
+});