diff --git a/frontend_tests/node_tests/composebox_typeahead.js b/frontend_tests/node_tests/composebox_typeahead.js
index 8b2be9ebdc..c8ec989bdb 100644
--- a/frontend_tests/node_tests/composebox_typeahead.js
+++ b/frontend_tests/node_tests/composebox_typeahead.js
@@ -174,7 +174,7 @@ set_global('compose', {
     finish: noop,
 });
 
-emoji.active_realm_emojis = {};
+emoji.active_realm_emojis = new Map();
 emoji.emojis_by_name = emojis_by_name;
 emoji.emojis = emoji_list;
 
diff --git a/frontend_tests/node_tests/emoji.js b/frontend_tests/node_tests/emoji.js
index e9eaf5af7d..854dc9a481 100644
--- a/frontend_tests/node_tests/emoji.js
+++ b/frontend_tests/node_tests/emoji.js
@@ -61,9 +61,9 @@ run_test('initialize', () => {
 });
 
 run_test('get_canonical_name', () => {
-    emoji.active_realm_emojis = {
+    emoji.active_realm_emojis = new Map(Object.entries({
         realm_emoji: 'TBD',
-    };
+    }));
     let canonical_name = emoji.get_canonical_name('realm_emoji');
     assert.equal(canonical_name, 'realm_emoji');
 
@@ -79,9 +79,9 @@ run_test('get_canonical_name', () => {
     canonical_name = emoji.get_canonical_name('+1');
     assert.equal(canonical_name, 'thumbs_up');
 
-    emoji.active_realm_emojis = {
+    emoji.active_realm_emojis = new Map(Object.entries({
         '+1': 'TBD',
-    };
+    }));
     canonical_name = emoji.get_canonical_name('+1');
     assert.equal(canonical_name, '+1');
 
diff --git a/frontend_tests/node_tests/reactions.js b/frontend_tests/node_tests/reactions.js
index fe3a43795a..3b596d6953 100644
--- a/frontend_tests/node_tests/reactions.js
+++ b/frontend_tests/node_tests/reactions.js
@@ -25,7 +25,7 @@ set_global('emoji', {
             deactivated: false,
         },
     })),
-    active_realm_emojis: {
+    active_realm_emojis: new Map(Object.entries({
         realm_emoji: {
             id: '991',
             emoji_name: 'realm_emoji',
@@ -36,7 +36,7 @@ set_global('emoji', {
             emoji_name: 'zulip',
             emoji_url: 'TBD',
         },
-    },
+    })),
     deactivated_realm_emojis: {
         inactive_realm_emoji: {
             emoji_name: 'inactive_realm_emoji',
diff --git a/frontend_tests/node_tests/typeahead_helper.js b/frontend_tests/node_tests/typeahead_helper.js
index 304bf91c59..ac4dd45271 100644
--- a/frontend_tests/node_tests/typeahead_helper.js
+++ b/frontend_tests/node_tests/typeahead_helper.js
@@ -652,9 +652,9 @@ run_test('render_emoji', () => {
         emoji_name: 'thumbs_up',
         emoji_code: '1f44d',
     };
-    emoji.active_realm_emojis = {
+    emoji.active_realm_emojis = new Map(Object.entries({
         realm_emoji: 'TBD',
-    };
+    }));
 
     global.stub_templates(function (template_name, args) {
         assert.equal(template_name, 'typeahead_list_item');
diff --git a/static/js/emoji.js b/static/js/emoji.js
index 4fa2fb1fb4..daf121fc5b 100644
--- a/static/js/emoji.js
+++ b/static/js/emoji.js
@@ -4,7 +4,7 @@
 exports.emojis_by_name = new Map();
 
 exports.all_realm_emojis = new Map();
-exports.active_realm_emojis = {};
+exports.active_realm_emojis = new Map();
 exports.default_emoji_aliases = {};
 
 const zulip_emoji = {
@@ -20,7 +20,7 @@ exports.update_emojis = function update_emojis(realm_emojis) {
     // to it. This makes sure that in case of deletion, the deleted realm_emojis
     // don't persist in exports.active_realm_emojis.
     exports.all_realm_emojis.clear();
-    exports.active_realm_emojis = {};
+    exports.active_realm_emojis.clear();
 
     _.each(realm_emojis, function (data) {
         exports.all_realm_emojis.set(data.id, {
@@ -30,14 +30,16 @@ exports.update_emojis = function update_emojis(realm_emojis) {
             deactivated: data.deactivated,
         });
         if (data.deactivated !== true) {
-            exports.active_realm_emojis[data.name] = {id: data.id,
-                                                      emoji_name: data.name,
-                                                      emoji_url: data.source_url};
+            exports.active_realm_emojis.set(data.name, {
+                id: data.id,
+                emoji_name: data.name,
+                emoji_url: data.source_url,
+            });
         }
     });
     // Add the Zulip emoji to the realm emojis list
-    exports.all_realm_emojis.zulip = zulip_emoji;
-    exports.active_realm_emojis.zulip = zulip_emoji;
+    exports.all_realm_emojis.set("zulip", zulip_emoji);
+    exports.active_realm_emojis.set("zulip", zulip_emoji);
 
     exports.build_emoji_data(exports.active_realm_emojis);
 };
@@ -76,7 +78,7 @@ exports.initialize = function initialize() {
 exports.build_emoji_data = function (realm_emojis) {
     exports.emojis_by_name.clear();
     let emoji_dict;
-    _.each(realm_emojis, function (realm_emoji, realm_emoji_name) {
+    for (const [realm_emoji_name, realm_emoji] of realm_emojis) {
         emoji_dict = {
             name: realm_emoji_name,
             display_name: realm_emoji_name,
@@ -86,7 +88,7 @@ exports.build_emoji_data = function (realm_emojis) {
             has_reacted: false,
         };
         exports.emojis_by_name.set(realm_emoji_name, emoji_dict);
-    });
+    }
 
     _.each(emoji_codes.emoji_catalog, function (codepoints) {
         _.each(codepoints, function (codepoint) {
@@ -129,7 +131,7 @@ exports.build_emoji_upload_widget = function () {
 };
 
 exports.get_canonical_name = function (emoji_name) {
-    if (exports.active_realm_emojis.hasOwnProperty(emoji_name)) {
+    if (exports.active_realm_emojis.has(emoji_name)) {
         return emoji_name;
     }
     if (!emoji_codes.name_to_codepoint.hasOwnProperty(emoji_name)) {
diff --git a/static/js/emoji_picker.js b/static/js/emoji_picker.js
index 5946725516..289d9fc1be 100644
--- a/static/js/emoji_picker.js
+++ b/static/js/emoji_picker.js
@@ -102,9 +102,9 @@ function show_emoji_catalog() {
 exports.generate_emoji_picker_data = function (realm_emojis) {
     exports.complete_emoji_catalog = {};
     exports.complete_emoji_catalog.Custom = [];
-    _.each(realm_emojis, function (realm_emoji, realm_emoji_name) {
+    for (const realm_emoji_name of realm_emojis.keys()) {
         exports.complete_emoji_catalog.Custom.push(emoji.emojis_by_name.get(realm_emoji_name));
-    });
+    }
 
     _.each(emoji_codes.emoji_catalog, function (codepoints, category) {
         exports.complete_emoji_catalog[category] = [];
@@ -243,7 +243,7 @@ function get_alias_to_be_used(message_id, emoji_name) {
     // the passed name as it is.
     const message = message_store.get(message_id);
     let aliases = [emoji_name];
-    if (!emoji.active_realm_emojis.hasOwnProperty(emoji_name)) {
+    if (!emoji.active_realm_emojis.has(emoji_name)) {
         if (emoji_codes.name_to_codepoint.hasOwnProperty(emoji_name)) {
             const codepoint = emoji_codes.name_to_codepoint[emoji_name];
             aliases = emoji.default_emoji_aliases[codepoint];
diff --git a/static/js/markdown.js b/static/js/markdown.js
index 7d49bb6912..02232cb09e 100644
--- a/static/js/markdown.js
+++ b/static/js/markdown.js
@@ -189,8 +189,8 @@ function handleUnicodeEmoji(unicode_emoji) {
 function handleEmoji(emoji_name) {
     const alt_text = ':' + emoji_name + ':';
     const title = emoji_name.split("_").join(" ");
-    if (emoji.active_realm_emojis.hasOwnProperty(emoji_name)) {
-        const emoji_url = emoji.active_realm_emojis[emoji_name].emoji_url;
+    if (emoji.active_realm_emojis.has(emoji_name)) {
+        const emoji_url = emoji.active_realm_emojis.get(emoji_name).emoji_url;
         return '<img alt="' + alt_text + '"' +
                ' class="emoji" src="' + emoji_url + '"' +
                ' title="' + title + '">';
diff --git a/static/js/reactions.js b/static/js/reactions.js
index 1f2005ce67..b56181bc04 100644
--- a/static/js/reactions.js
+++ b/static/js/reactions.js
@@ -119,13 +119,13 @@ exports.toggle_emoji_reaction = function (message_id, emoji_name) {
         emoji_name: emoji_name,
     };
 
-    if (emoji.active_realm_emojis.hasOwnProperty(emoji_name)) {
+    if (emoji.active_realm_emojis.has(emoji_name)) {
         if (emoji_name === 'zulip') {
             reaction_info.reaction_type = 'zulip_extra_emoji';
         } else {
             reaction_info.reaction_type = 'realm_emoji';
         }
-        reaction_info.emoji_code = emoji.active_realm_emojis[emoji_name].id;
+        reaction_info.emoji_code = emoji.active_realm_emojis.get(emoji_name).id;
     } else if (emoji_codes.name_to_codepoint.hasOwnProperty(emoji_name)) {
         reaction_info.reaction_type = 'unicode_emoji';
         reaction_info.emoji_code = emoji_codes.name_to_codepoint[emoji_name];
diff --git a/static/js/typeahead_helper.js b/static/js/typeahead_helper.js
index dc961817aa..62c1bd8b32 100644
--- a/static/js/typeahead_helper.js
+++ b/static/js/typeahead_helper.js
@@ -148,7 +148,7 @@ exports.render_emoji = function (item) {
         is_emoji: true,
         primary: item.emoji_name.split("_").join(" "),
     };
-    if (emoji.active_realm_emojis.hasOwnProperty(item.emoji_name)) {
+    if (emoji.active_realm_emojis.has(item.emoji_name)) {
         args.img_src = item.emoji_url;
     } else {
         args.emoji_code = item.emoji_code;