From 8442d370f4f21b813305da473dca908217436977 Mon Sep 17 00:00:00 2001
From: Bob Bergman <robert.bergman@gmail.com>
Date: Thu, 21 Jan 2021 13:08:18 -0700
Subject: [PATCH] perf(topics): avoid recomputing topics in loop

Aims to fix or improve #101
---
 src/index.ts | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/index.ts b/src/index.ts
index d42db64d..154b8374 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -67,9 +67,12 @@ export default class Help extends HelpBase {
    * and this can be removed.
    */
   private get _topics(): Config.Topic[] {
-    return this.config.topics.filter((topic: Config.Topic) => {
+    // since this.config.topics is a getter that does non-trivial work, cache it outside the filter loop for
+    // performance benefits in the presence of large numbers of topics
+    const topics = this.config.topics
+    return topics.filter((topic: Config.Topic) => {
       // it is assumed a topic has a child if it has children
-      const hasChild = this.config.topics.some(subTopic => subTopic.name.includes(`${topic.name}:`))
+      const hasChild = topics.some(subTopic => subTopic.name.includes(`${topic.name}:`))
       return hasChild
     })
   }