diff --git a/modules/helfi_toc/assets/js/tableOfContents.js b/modules/helfi_toc/assets/js/tableOfContents.js
index 634903968..5ace846b2 100644
--- a/modules/helfi_toc/assets/js/tableOfContents.js
+++ b/modules/helfi_toc/assets/js/tableOfContents.js
@@ -1,21 +1,23 @@
 'use strict';
 
-(function (Drupal, once) {
+(function (Drupal, once, drupalSettings) {
   Drupal.behaviors.table_of_contents = {
     attach: function attach() {
 
       function findAvailableId(name, reserved, anchors, count) {
         let newName = name;
         if (count > 0) { // Only when headings are not unique on page we want to add counter
-          newName += '-' + count;
+          newName += `-${count}`;
         }
         if (reserved.includes(newName)) {
-          return findAvailableId(name, reserved, anchors, ++count);
-        } else if (anchors.includes(newName)) {
+          return findAvailableId(name, reserved, anchors, count + 1);
+        }
+
+        if (anchors.includes(newName)) {
           if (count === 0) {
-            count++; // When reserved heading is visible on page, lets start counting from 2 instead of 1
+            count += 1; // When reserved heading is visible on page, lets start counting from 2 instead of 1
           }
-          return findAvailableId(name, reserved, anchors, ++count);
+          return findAvailableId(name, reserved, anchors, count + 1);
         }
         return newName;
       }
@@ -32,33 +34,125 @@
 
       // Exclude elements from TOC that are not content:
       // e.g. TOC, sidebar, cookie compliency-banner etc.
-      const exclusions = '' +
+      const exclusions =
+        '' +
         ':not(.layout-sidebar-first *)' +
         ':not(.layout-sidebar-second *)' +
         ':not(.tools__container *)' +
         ':not(.breadcrumb__container *)' +
         ':not(#helfi-toc-table-of-contents *)' +
         ':not(.embedded-content-cookie-compliance *)' +
-        ':not(.react-and-share-cookie-compliance *)'
+        ':not(.react-and-share-cookie-compliance *)';
 
       const titleComponents = [
-        'h2'+exclusions,
-        'h3'+exclusions,
-        'h4'+exclusions,
-        'h5'+exclusions,
-        'h6'+exclusions,
+        `h2${exclusions}`,
+        `h3${exclusions}`,
+        `h4${exclusions}`,
+        `h5${exclusions}`,
+        `h6${exclusions}`,
       ];
 
+      const mainLanguages = [
+        'en',
+        'fi',
+        'sv',
+      ];
+
+      const swaps = {
+        '0': '[°₀۰０]',
+        '1': '[¹₁۱１]',
+        '2': '[²₂۲２]',
+        '3': '[³₃۳３]',
+        '4': '[⁴₄۴٤４]',
+        '5': '[⁵₅۵٥５]',
+        '6': '[⁶₆۶٦６]',
+        '7': '[⁷₇۷７]',
+        '8': '[⁸₈۸８]',
+        '9': '[⁹₉۹９]',
+        'a': '[àáảãạăắằẳẵặâấầẩẫậāąåαάἀἁἂἃἄἅἆἇᾀᾁᾂᾃᾄᾅᾆᾇὰᾰᾱᾲᾳᾴᾶᾷаأအာါǻǎªაअاａä]',
+        'b': '[бβبဗბｂब]',
+        'c': '[çćčĉċｃ©]',
+        'd': '[ďðđƌȡɖɗᵭᶁᶑдδدضဍဒდｄᴅᴆ]',
+        'e': '[éèẻẽẹêếềểễệëēęěĕėεέἐἑἒἓἔἕὲеёэєəဧေဲეएإئｅ]',
+        'f': '[фφفƒფｆ]',
+        'g': '[ĝğġģгґγဂგگｇ]',
+        'h': '[ĥħηήحهဟှჰｈ]',
+        'i': '[íìỉĩịîïīĭįıιίϊΐἰἱἲἳἴἵἶἷὶῐῑῒῖῗіїиဣိီည်ǐიइیｉi̇ϒ]',
+        'j': '[ĵјჯجｊ]',
+        'k': '[ķĸкκقكကკქکｋ]',
+        'l': '[łľĺļŀлλلလლｌल]',
+        'm': '[мμمမმｍ]',
+        'n': '[ñńňņʼnŋνнنနნｎ]',
+        'o': '[óòỏõọôốồổỗộơớờởỡợøōőŏοὀὁὂὃὄὅὸόоوθိုǒǿºოओｏöө]',
+        'p': '[пπပპپｐ]',
+        'q': '[ყｑ]',
+        'r': '[ŕřŗрρرრｒ]',
+        's': '[śšşсσșςسصစſსｓŝ]',
+        't': '[ťţтτțتطဋတŧთტｔ]',
+        'u': '[úùủũụưứừửữựûūůűŭųµуဉုူǔǖǘǚǜუउｕўü]',
+        'v': '[вვϐｖ]',
+        'w': '[ŵωώဝွｗ]',
+        'x': '[χξｘ]',
+        'y': '[ýỳỷỹỵÿŷйыυϋύΰيယｙῠῡὺ]',
+        'z': '[źžżзζزဇზｚ]',
+        'aa': '[عआآ]',
+        'ae': '[æǽ]',
+        'ai': '[ऐ]',
+        'ch': '[чჩჭچ]',
+        'dj': '[ђđ]',
+        'dz': '[џძ]',
+        'ei': '[ऍ]',
+        'gh': '[غღ]',
+        'ii': '[ई]',
+        'ij': '[ij]',
+        'kh': '[хخხ]',
+        'lj': '[љ]',
+        'nj': '[њ]',
+        'oe': '[öœؤ]',
+        'oi': '[ऑ]',
+        'oii': '[ऒ]',
+        'ps': '[ψ]',
+        'sh': '[шშش]',
+        'shch': '[щ]',
+        'ss': '[ß]',
+        'sx': '[ŝ]',
+        'th': '[þϑثذظ]',
+        'ts': '[цცწ]',
+        'ue': '[ü]',
+        'uu': '[ऊ]',
+        'ya': '[я]',
+        'yu': '[ю]',
+        'zh': '[жჟژ]',
+        'gx': '[ĝ]',
+        'hx': '[ĥ]',
+        'jx': '[ĵ]',
+      };
+
       // Craft table of contents.
       once('table-of-contents', titleComponents.join(','), mainContent)
         .forEach(function (content) {
-          const name = content.textContent
+          let name = content.textContent
             .toLowerCase()
-            .trim()
-            .replace(/ä/gi, 'a')
-            .replace(/ö/gi, 'o')
-            .replace(/å/gi, 'a')
+            .trim();
+
+          // To ensure backwards compatibility, this is done only to "other" languages.
+          if (!mainLanguages.includes(drupalSettings.path.currentLanguage)) {
+            Object.keys(swaps).forEach((swap) => {
+              name = name.replace(new RegExp(swaps[swap], 'g'), swap);
+            });
+          }
+          else {
+            name = name
+              .replace(/ä/gi, 'a')
+              .replace(/ö/gi, 'o')
+              .replace(/å/gi, 'a');
+          }
+
+          name = name
+            // Replace any remaining non-word character including whitespace with '-'.
+            // This leaves only characters matching [A-Za-z0-9-_] to the name.
             .replace(/\W/g, '-')
+            // Use underscore at the end of the string: 'example-1' -> 'example_1'.
             .replace(/-(\d+)$/g, '_$1');
 
           let nodeName = content.nodeName.toLowerCase();
@@ -73,13 +167,13 @@
           anchors.push(anchorName);
 
           // Create table of contents if component is enabled.
-          if (tableOfContentsList && nodeName === "h2") {
+          if (tableOfContentsList && nodeName === 'h2') {
             let listItem = document.createElement('li');
             listItem.classList.add('table-of-contents__item');
 
             let link = document.createElement('a');
             link.classList.add('table-of-contents__link');
-            link.href = '#' + anchorName;
+            link.href = `#${anchorName}`;
             link.textContent = content.textContent.trim();
 
             listItem.appendChild(link);
@@ -98,4 +192,4 @@
       }
     },
   };
-})(Drupal, once);
+})(Drupal, once, drupalSettings);