From d7b898da28993343a719601c871592653318c885 Mon Sep 17 00:00:00 2001
From: michaelkix <michaelg@redkix.com>
Date: Wed, 6 Jun 2018 16:13:34 +0300
Subject: [PATCH] perf: don't reflow when there's no class to add

Avoid an unnecessary reflow in the CSSTransition component if the class
name is falsy.
---
 src/CSSTransition.js | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/CSSTransition.js b/src/CSSTransition.js
index 239d9671..0a335b70 100644
--- a/src/CSSTransition.js
+++ b/src/CSSTransition.js
@@ -210,10 +210,12 @@ class CSSTransition extends React.Component {
   reflowAndAddClass(node, className) {
     // This is for to force a repaint,
     // which is necessary in order to transition styles when adding a class name.
-    /* eslint-disable no-unused-expressions */
-    node && node.scrollTop;
-    /* eslint-enable no-unused-expressions */
-    addClass(node, className);
+    if (className) {
+      /* eslint-disable no-unused-expressions */
+      node && node.scrollTop;
+      /* eslint-enable no-unused-expressions */
+      addClass(node, className);
+    }
   }
 
   render() {