basepath config as singleton

src/routing/basePath.js

@@ -0,0 +1,10 @@
+const base = document.querySelector('base');
+
+let basePath;
+if (base && base.href) {
+  basePath = base.attributes.getNamedItem('href').value;
+} else {
+  basePath = '';
+}
+
+export default basePath;

src/routing/history.js

@@ -1,10 +1,10 @@
 import { createHistory } from 'history';
 import { useRouterHistory } from 'react-router';
 import { syncHistoryWithStore } from 'react-router-redux';
+import basePath from './basePath';
 
-const base = document.querySelector('base');
 let history = useRouterHistory(createHistory)({
-  basename: base && base.href || ''
+  basename: basePath
 });
 
 const syncHistory = (store) => {