Updated version-select.js (#711)

docs/js/version-select.js

@@ -1,62 +1,64 @@
 /*
  * Custom version of same taken from mike code for injecting version switcher into percona.com
-*/
+ */
 
-window.addEventListener("DOMContentLoaded", function() {
+window.addEventListener('DOMContentLoaded', function () {
   // This is a bit hacky. Figure out the base URL from a known CSS file the
   // template refers to...
-  var ex = new RegExp("/?css/version-select.css$");
+  var ex = new RegExp('/?css/version-select.css$');
   var sheet = document.querySelector('link[href$="version-select.css"]');
 
-  var ABS_BASE_URL = sheet.href.replace(ex, "");
-  var CURRENT_VERSION = ABS_BASE_URL.split("/").pop();
+  if (!sheet) {
+    return;
+  }
+
+  var ABS_BASE_URL = sheet.href.replace(ex, '');
+  var CURRENT_VERSION = ABS_BASE_URL.split('/').pop();
 
   function makeSelect(options, selected) {
-    var select = document.createElement("select");
-//    select.classList.add("form-control");
-    select.classList.add("btn");
-    select.classList.add("btn-primary");
-
-    options.forEach(function(i) {
-      var option = new Option(i.text, i.value, undefined,
-                              i.value === selected);
+    var select = document.createElement('select');
+    select.classList.add('btn');
+    select.classList.add('btn-primary');
+
+    options.forEach(function (i) {
+      var option = new Option(i.text, i.value, undefined, i.value === selected);
       select.add(option);
     });
 
     return select;
   }
 
   var xhr = new XMLHttpRequest();
-  xhr.open("GET", ABS_BASE_URL + "/../versions.json");
-  xhr.onload = function() {
+  xhr.open('GET', ABS_BASE_URL + '/../versions.json');
+  xhr.onload = function () {
     var versions = JSON.parse(this.responseText);
 
-    var realVersion = versions.find(function(i) {
-      return i.version === CURRENT_VERSION ||
-             i.aliases.includes(CURRENT_VERSION);
+    var realVersion = versions.find(function (i) {
+      return (
+        i.version === CURRENT_VERSION || i.aliases.includes(CURRENT_VERSION)
+      );
     }).version;
 
-    var select = makeSelect(versions.map(function(i) {
-      return {text: i.title, value: i.version};
-    }), realVersion);
-    select.addEventListener("change", function(event) {
-      window.location.href = ABS_BASE_URL + "/../" + this.value;
+    var select = makeSelect(
+      versions.map(function (i) {
+        return { text: i.title, value: i.version };
+      }),
+      realVersion
+    );
+    select.addEventListener('change', function (event) {
+      window.location.href = ABS_BASE_URL + '/../' + this.value;
     });
 
-    var container = document.createElement("div");
-    container.id = "custom_select";
-    container.classList.add("side-column-block");
-
-    // Label
-//    var label = document.createElement("span");
-//    label.textContent = "PMM version: ";
-//    container.appendChild(label);
+    var container = document.createElement('div');
+    container.id = 'custom_select';
+    container.classList.add('side-column-block');
 
     // Add menu
     container.appendChild(select);
 
-    var sidebar = document.querySelector("#version-select-wrapper"); // Inject menu into element with this ID
+    var sidebar = document.querySelector('#version-select-wrapper'); // Inject menu into element with this ID
     sidebar.appendChild(container);
   };
+
   xhr.send();
-});
+});