Polish DocumentToggle.js

* Declare duplicate jQuery selectors as variables
* Remove extra semicolons after function declarations
* Remove leftover jquery.js from Java/XML toggle implementation

When the Java/XML toggle implementation was introduced,
jquery-3.2.1.min.js replaced the old jquery script in toggle.adoc
and the old jquery script was accidentally leftover as a result.

spring-batch-docs/asciidoc/js/DocumentToggle.js

@@ -1,5 +1,15 @@
 $(document).ready(function(){
 
+    var $xmlButton = $("#xmlButton");
+    var $javaButton = $("#javaButton");
+    var $bothButton = $("#bothButton");
+
+    var $xmlContent = $("*.xmlContent");
+    var $xmlContentAll = $("*.xmlContent > *");
+
+    var $javaContent = $("*.javaContent");
+    var $javaContentAll = $("*.javaContent > *");
+
     setJava();
 
     // Initial cookie handler. This part remembers the reader's choice and sets the toggle
@@ -7,58 +17,58 @@ $(document).ready(function(){
     var docToggleCookieString = Cookies.get("docToggle");
     if (docToggleCookieString != null) {
         if (docToggleCookieString === "xml") {
-            $("#xmlButton").prop("checked", true);
+            $xmlButton.prop("checked", true);
             setXml();
         } else if (docToggleCookieString === "java") {
-            $("#javaButton").prop("checked", true);
+            $javaButton.prop("checked", true);
             setJava();
         } else if (docToggleCookieString === "both") {
-            $("#bothButton").prop("checked", true);
+            $bothButton.prop("checked", true);
             setBoth();
         }
     }
 
     // Click handlers
-    $("#xmlButton").on("click", function() {
+    $xmlButton.on("click", function() {
         setXml();
     });
-    $("#javaButton").on("click", function() {
+    $javaButton.on("click", function() {
         setJava();
     });
-    $("#bothButton").on("click", function() {
+    $bothButton.on("click", function() {
         setBoth();
     });
 
     // Functions to do the work of handling the reader's choice, whether through a click
     // or through a cookie. 3652 days is 10 years, give or take a leap day.
     function setXml() {
-        $("*.xmlContent").show();
-        $("*.javaContent").hide();
-        $("*.javaContent > *").addClass("js-toc-ignore");
-        $("*.xmlContent > *").removeClass("js-toc-ignore");
+        $xmlContent.show();
+        $javaContent.hide();
+        $javaContentAll.addClass("js-toc-ignore");
+        $xmlContentAll.removeClass("js-toc-ignore");
         window.dispatchEvent(new Event("tocRefresh"));
         tocbot.refresh();
         Cookies.set('docToggle', 'xml', { expires: 3652 });
-    };
+    }
 
     function setJava() {
-        $("*.javaContent").show();
-        $("*.xmlContent").hide();
-        $("*.xmlContent > *").addClass("js-toc-ignore");
-        $("*.javaContent > *").removeClass("js-toc-ignore");
+        $javaContent.show();
+        $xmlContent.hide();
+        $xmlContentAll.addClass("js-toc-ignore");
+        $javaContentAll.removeClass("js-toc-ignore");
         window.dispatchEvent(new Event("tocRefresh"));
         tocbot.refresh();
         Cookies.set('docToggle', 'java', { expires: 3652 });
-    };
+    }
 
     function setBoth() {
-        $("*.javaContent").show();
-        $("*.xmlContent").show();
-        $("*.javaContent > *").removeClass("js-toc-ignore");
-        $("*.xmlContent > *").removeClass("js-toc-ignore");
+        $javaContent.show();
+        $xmlContent.show();
+        $javaContentAll.removeClass("js-toc-ignore");
+        $xmlContentAll.removeClass("js-toc-ignore");
         window.dispatchEvent(new Event("tocRefresh"));
         tocbot.refresh();
         Cookies.set('docToggle', 'both', { expires: 3652 });
-    };
+    }
 
 });