From f92f62738d688a504049b4389f1dad42f5d495ef Mon Sep 17 00:00:00 2001
From: Justin Ridgewell <justin@ridgewell.name>
Date: Tue, 12 Feb 2019 20:24:26 -0500
Subject: [PATCH] Optimize scopeSelector (#20819)

https://jsbench.github.io/#e00c46505b5b875d2dcd5894d6e46adc
---
 src/dom.js | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/src/dom.js b/src/dom.js
index 1dcc0e9bb0d7..4058b4452099 100644
--- a/src/dom.js
+++ b/src/dom.js
@@ -528,15 +528,12 @@ function isScopeSelectorSupported(parent) {
  *   scopeSelector('article >', 'div, ul');     // article > div, article > ul
  * ```
  *
- * @param {string} ancestorSelector
- * @param {string} descendantSelector
+ * @param {string} distribute
+ * @param {string} selector
  * @return {string}
  */
-function scopeSelector(ancestorSelector, descendantSelector) {
-  return descendantSelector
-      .split(',')
-      .map(subSelector => `${ancestorSelector} ${subSelector}`)
-      .join(',');
+function scopeSelector(distribute, selector) {
+  return selector.replace(/^|,/g, `$&${distribute} `);
 }
 
 export const scopeSelectorForTesting = scopeSelector;