add underline extension

packages/extension-underline/index.ts

@@ -0,0 +1,35 @@
+import { Mark } from '@tiptap/core'
+
+declare module '@tiptap/core/src/Editor' {
+  interface Editor {
+    underline(): Editor,
+  }
+}
+
+export const inputRegex = /(?:^|\s)((?:~)((?:[^~]+))(?:~))$/gm
+export const pasteRegex = /(?:^|\s)((?:~)((?:[^~]+))(?:~))/gm
+
+export default new Mark()
+  .name('underline')
+  .schema(() => ({
+    parseDOM: [
+      {
+        tag: 'u',
+      },
+      {
+        style: 'text-decoration',
+        getAttrs: node => node === 'underline' ? {} : false,
+      },
+    ],
+    toDOM: () => ['u', 0],
+  }))
+  .commands(({ editor, name }) => ({
+    underline: next => () => {
+      editor.toggleMark(name)
+      next()
+    },
+  }))
+  .keys(({ editor }) => ({
+    'Mod-u': () => editor.underline()
+  }))
+  .create()