add placeholder extension

packages/extension-placeholder/src/index.ts

@@ -0,0 +1,5 @@
+import { Placeholder } from './placeholder'
+
+export * from './placeholder'
+
+export default Placeholder

packages/extension-placeholder/src/placeholder.ts

@@ -0,0 +1,67 @@
+import { Extension, isNodeEmpty } from '@tiptap/core'
+import { Decoration, DecorationSet } from 'prosemirror-view'
+import { Plugin } from 'prosemirror-state'
+
+export interface PlaceholderOptions {
+  emptyEditorClass: string,
+  emptyNodeClass: string,
+  placeholder: string | Function,
+  showOnlyWhenEditable: boolean,
+  showOnlyCurrent: boolean,
+}
+
+export const Placeholder = Extension.create<PlaceholderOptions>({
+  name: 'placeholder',
+
+  defaultOptions: {
+    emptyEditorClass: 'is-editor-empty',
+    emptyNodeClass: 'is-empty',
+    placeholder: 'Write something …',
+    showOnlyWhenEditable: true,
+    showOnlyCurrent: true,
+  },
+
+  addProseMirrorPlugins() {
+    return [
+      new Plugin({
+        props: {
+          decorations: ({ doc, selection }) => {
+            const active = this.editor.isEditable || !this.options.showOnlyWhenEditable
+            const { anchor } = selection
+            const decorations: Decoration[] = []
+
+            if (!active) {
+              return
+            }
+
+            doc.descendants((node, pos) => {
+              const hasAnchor = anchor >= pos && anchor <= (pos + node.nodeSize)
+              const isEmpty = !node.isLeaf && isNodeEmpty(node)
+
+              if ((hasAnchor || !this.options.showOnlyCurrent) && isEmpty) {
+                const classes = [this.options.emptyNodeClass]
+
+                if (this.editor.isEmpty) {
+                  classes.push(this.options.emptyEditorClass)
+                }
+
+                const decoration = Decoration.node(pos, pos + node.nodeSize, {
+                  class: classes.join(' '),
+                  'data-placeholder': typeof this.options.placeholder === 'function'
+                    ? this.options.placeholder(node)
+                    : this.options.placeholder,
+                })
+
+                decorations.push(decoration)
+              }
+
+              return false
+            })
+
+            return DecorationSet.create(doc, decorations)
+          },
+        },
+      }),
+    ]
+  },
+})