prerender dark theme

gatsby-ssr.js

@@ -1 +1,21 @@
+import React from 'react';
 import 'firebase/database';
+
+const OnDark = () => {
+  const codeToRunOnClient = `
+    if (localStorage.getItem('dark') || (new Date().getHours() >= 22 || new Date().getHours() <= 6)) {
+      document.body.classList.add('dark')
+      window.localStorage.setItem('dark', 'true')
+    }
+  `;
+
+  return (
+    <script
+      dangerouslySetInnerHTML={{ __html: codeToRunOnClient }}
+    />
+  )
+}
+
+export const onRenderBody = ({ setPreBodyComponents }) => {
+  setPreBodyComponents(<OnDark key='isDarkTheme' />)
+}

src/context/ThemeContext.js

@@ -18,8 +18,8 @@ const ThemeProvider = ({ children }) => {
   }
 
   React.useEffect(() => {
-    if (localStorage.getItem('dark') || (new Date().getHours() >= 22 || new Date().getHours() <= 6)) {
-      toggleDarkTheme()
+    if (localStorage.getItem('dark')) {
+      setIsDark(true)
     }
   }, [setIsDark])