add basic highlight extension

packages/extension-highlight/index.ts

@@ -0,0 +1,31 @@
+import {
+  Command, Mark,
+} from '@tiptap/core'
+
+export type HighlightCommand = () => Command
+
+declare module '@tiptap/core/src/Editor' {
+  interface Commands {
+    highlight: HighlightCommand,
+  }
+}
+
+export default new Mark()
+  .name('highlight')
+  .schema(() => ({
+    parseDOM: [
+      {
+        tag: 'mark',
+      },
+    ],
+    toDOM: () => ['mark', 0],
+  }))
+  .commands(({ name }) => ({
+    highlight: () => ({ commands }) => {
+      return commands.toggleMark(name)
+    },
+  }))
+  .keys(({ editor }) => ({
+    'Mod-e': () => editor.highlight(),
+  }))
+  .create()