refactoring

Resolve #7779

packages/backend/src/misc/extract-mentions.ts

@@ -0,0 +1,11 @@
+// test is located in test/extract-mentions
+
+import * as mfm from 'mfm-js';
+
+export function extractMentions(nodes: mfm.MfmNode[]): mfm.MfmMention['props'][] {
+	// TODO: 重複を削除
+	const mentionNodes = mfm.extract(nodes, (node) => node.type === 'mention');
+	const mentions = mentionNodes.map(x => x.props);
+
+	return mentions;
+}