diff --git a/django/contrib/admin/static/admin/js/SelectFilter2.js b/django/contrib/admin/static/admin/js/SelectFilter2.js
index 9541da13d1..aa49254257 100644
--- a/django/contrib/admin/static/admin/js/SelectFilter2.js
+++ b/django/contrib/admin/static/admin/js/SelectFilter2.js
@@ -26,10 +26,10 @@ Requires jQuery, core.js, and SelectBox.js.
 
             var ps = from_box.parentNode.getElementsByTagName('p');
             for (var i = 0; i < ps.length; i++) {
-                if (ps[i].className.indexOf("info") !== -1) {
+                if (ps[i].classList.contains("info")) {
                     // Remove <p class="info">, because it just gets in the way.
                     from_box.parentNode.removeChild(ps[i]);
-                } else if (ps[i].className.indexOf("help") !== -1) {
+                } else if (ps[i].classList.contains("help")) {
                     // Move help text up to the top so it isn't below the select
                     // boxes or wrapped off on the side to the right of the add
                     // button:
@@ -112,7 +112,7 @@ Requires jQuery, core.js, and SelectBox.js.
 
             // Set up the JavaScript event handlers for the select box filter interface
             var move_selection = function(e, elem, move_func, from, to) {
-                if (elem.className.indexOf('active') !== -1) {
+                if (elem.classList.contains('active')) {
                     move_func(from, to);
                     SelectFilter.refresh_icons(field_id);
                 }
diff --git a/django/contrib/admin/static/admin/js/admin/DateTimeShortcuts.js b/django/contrib/admin/static/admin/js/admin/DateTimeShortcuts.js
index a2ef721ee5..f04dbc51bf 100644
--- a/django/contrib/admin/static/admin/js/admin/DateTimeShortcuts.js
+++ b/django/contrib/admin/static/admin/js/admin/DateTimeShortcuts.js
@@ -38,11 +38,11 @@
             var inputs = document.getElementsByTagName('input');
             for (var i = 0; i < inputs.length; i++) {
                 var inp = inputs[i];
-                if (inp.type === 'text' && inp.className.match(/vTimeField/)) {
+                if (inp.type === 'text' && inp.classList.contains('vTimeField')) {
                     DateTimeShortcuts.addClock(inp);
                     DateTimeShortcuts.addTimezoneWarning(inp);
                 }
-                else if (inp.type === 'text' && inp.className.match(/vDateField/)) {
+                else if (inp.type === 'text' && inp.classList.contains('vDateField')) {
                     DateTimeShortcuts.addCalendar(inp);
                     DateTimeShortcuts.addTimezoneWarning(inp);
                 }
diff --git a/django/contrib/admin/static/admin/js/admin/RelatedObjectLookups.js b/django/contrib/admin/static/admin/js/admin/RelatedObjectLookups.js
index f4c57c40e5..4f507be4b2 100644
--- a/django/contrib/admin/static/admin/js/admin/RelatedObjectLookups.js
+++ b/django/contrib/admin/static/admin/js/admin/RelatedObjectLookups.js
@@ -44,7 +44,7 @@
     function dismissRelatedLookupPopup(win, chosenId) {
         var name = windowname_to_id(win.name);
         var elem = document.getElementById(name);
-        if (elem.className.indexOf('vManyToManyRawIdAdminField') !== -1 && elem.value) {
+        if (elem.classList.contains('vManyToManyRawIdAdminField') && elem.value) {
             elem.value += ',' + chosenId;
         } else {
             document.getElementById(name).value = chosenId;
@@ -81,7 +81,7 @@
             if (elemName === 'SELECT') {
                 elem.options[elem.options.length] = new Option(newRepr, newId, true, true);
             } else if (elemName === 'INPUT') {
-                if (elem.className.indexOf('vManyToManyRawIdAdminField') !== -1 && elem.value) {
+                if (elem.classList.contains('vManyToManyRawIdAdminField') && elem.value) {
                     elem.value += ',' + newId;
                 } else {
                     elem.value = newId;
diff --git a/django/contrib/gis/static/gis/js/OLMapWidget.js b/django/contrib/gis/static/gis/js/OLMapWidget.js
index 0aca1c9d88..a50aa999e6 100644
--- a/django/contrib/gis/static/gis/js/OLMapWidget.js
+++ b/django/contrib/gis/static/gis/js/OLMapWidget.js
@@ -8,7 +8,7 @@ var GeometryTypeControl = function(opt_options) {
     var element = document.createElement('div');
     element.className = 'switch-type type-' + options.type + ' ol-control ol-unselectable';
     if (options.active) {
-        element.className += " type-active";
+        element.classList.add("type-active");
     }
 
     var self = this;
@@ -21,10 +21,9 @@ var GeometryTypeControl = function(opt_options) {
                 type: options.type
             });
             options.widget.map.addInteraction(options.widget.interactions.draw);
-            var className = options.widget.currentGeometryType.element.className.replace(/ type-active/g, '');
-            options.widget.currentGeometryType.element.className = className;
+            options.widget.currentGeometryType.element.classList.remove('type-active');
             options.widget.currentGeometryType = self;
-            element.className += " type-active";
+            element.classList.add("type-active");
         }
     };