From e0dc1b48ecb93256ea7a5726b12665a21b9c489e Mon Sep 17 00:00:00 2001
From: Jake Archibald <jaffathecake@gmail.com>
Date: Thu, 2 Aug 2018 16:52:11 +0100
Subject: [PATCH] Creating new objects rather than mutating existing objects.
 Fixes #121.

---
 src/components/Options/index.tsx | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/components/Options/index.tsx b/src/components/Options/index.tsx
index 348f9245..97bcbe10 100644
--- a/src/components/Options/index.tsx
+++ b/src/components/Options/index.tsx
@@ -81,10 +81,18 @@ export default class Options extends Component<Props, State> {
   onPreprocessorEnabledChange(event: Event) {
     const el = event.currentTarget as HTMLInputElement;
 
-    const preprocessorState = this.props.preprocessorState;
-    const preprocessor = el.name.split('.')[0] as keyof typeof preprocessorState;
-    preprocessorState[preprocessor].enabled = el.checked;
-    this.props.onPreprocessorOptionsChange(preprocessorState);
+    const newPreprocessorState = {
+      ...this.props.preprocessorState,
+    };
+
+    const preprocessor = el.name.split('.')[0] as keyof typeof newPreprocessorState;
+
+    newPreprocessorState[preprocessor] = {
+      ...newPreprocessorState[preprocessor],
+      enabled: el.checked,
+    };
+
+    this.props.onPreprocessorOptionsChange(newPreprocessorState);
   }
 
   @bind