refactor(defaultTheme): simplify script logic

Author: marjune163

src/tpl/defaultTheme/frontend/index.js

@@ -137,8 +137,9 @@
 			}
 
 			window.addEventListener('pagehide', function () {
-				if (input.value) {
-					sessionStorage.setItem(location.pathname, input.value);
+				const inputValue = input.value;
+				if (inputValue) {
+					sessionStorage.setItem(location.pathname, inputValue);
 				}
 			});