Use exact comparison operators

Author: AA-Turner

templates/switchers.js

@@ -55,7 +55,7 @@
   function navigate_to_first_existing(urls) {
     // Navigate to the first existing URL in urls.
     const url = urls.shift();
-    if (urls.length == 0 || url.startsWith("file:///")) {
+    if (urls.length === 0 || url.startsWith("file:///")) {
       window.location.href = url;
       return;
     }
@@ -79,7 +79,7 @@
     const current_version = version_segment_from_url();
     const new_url = url.replace('/' + current_language + current_version,
                                 '/' + current_language + selected_version);
-    if (new_url != url) {
+    if (new_url !== url) {
       navigate_to_first_existing([
         new_url,
         url.replace('/' + current_language + current_version,
@@ -96,11 +96,11 @@
     const url = window.location.href;
     const current_language = language_segment_from_url();
     const current_version = version_segment_from_url();
-    if (selected_language == 'en/') // Special 'default' case for English.
+    if (selected_language === 'en/') // Special 'default' case for English.
       selected_language = '';
     let new_url = url.replace('/' + current_language + current_version,
                               '/' + selected_language + current_version);
-    if (new_url != url) {
+    if (new_url !== url) {
       navigate_to_first_existing([
         new_url,
         '/'