diff --git a/static/js/bot_data.js b/static/js/bot_data.js
index 06105424f2..381691d0f0 100644
--- a/static/js/bot_data.js
+++ b/static/js/bot_data.js
@@ -48,7 +48,7 @@ export function update(bot_id, bot_update) {
 
     // We currently only support one service per bot.
     const service = services.get(bot_id)[0];
-    if (typeof bot_update.services !== "undefined" && bot_update.services.length > 0) {
+    if (bot_update.services !== undefined && bot_update.services.length > 0) {
         Object.assign(service, _.pick(bot_update.services[0], services_fields));
     }
 }
diff --git a/static/js/browser_history.js b/static/js/browser_history.js
index c254235809..18f94c5fa2 100644
--- a/static/js/browser_history.js
+++ b/static/js/browser_history.js
@@ -5,7 +5,7 @@ import * as ui_util from "./ui_util";
 const state = {
     is_internal_change: false,
     hash_before_overlay: null,
-    old_hash: typeof window !== "undefined" ? window.location.hash : "#",
+    old_hash: window.location.hash,
 };
 
 export function clear_for_testing() {
diff --git a/static/js/local_message.js b/static/js/local_message.js
index 6ef74f963a..42847e9353 100644
--- a/static/js/local_message.js
+++ b/static/js/local_message.js
@@ -19,7 +19,7 @@ export const get_next_id_float = (function () {
     return function () {
         const local_id_increment = 0.01;
         let latest = page_params.max_message_id;
-        if (typeof message_list.all !== "undefined" && message_list.all.last() !== undefined) {
+        if (message_list.all.last() !== undefined) {
             latest = message_list.all.last().id;
         }
         latest = Math.max(0, latest);
diff --git a/static/js/localstorage.js b/static/js/localstorage.js
index ad261478e8..68dcdf5930 100644
--- a/static/js/localstorage.js
+++ b/static/js/localstorage.js
@@ -120,7 +120,7 @@ export const localstorage = function () {
         },
 
         set(name, data) {
-            if (typeof _data.VERSION !== "undefined") {
+            if (_data.VERSION !== undefined) {
                 ls.setData(_data.VERSION, name, data, _data.expires);
 
                 // if the expires attribute was not set as a global, then
diff --git a/static/js/settings_invites.js b/static/js/settings_invites.js
index 8ee2c12c31..a6e0821956 100644
--- a/static/js/settings_invites.js
+++ b/static/js/settings_invites.js
@@ -122,11 +122,8 @@ function do_revoke_invite() {
     });
 }
 
-export function set_up(initialize_event_handlers) {
+export function set_up(initialize_event_handlers = true) {
     meta.loaded = true;
-    if (typeof initialize_event_handlers === "undefined") {
-        initialize_event_handlers = true;
-    }
 
     // create loading indicators
     loading.make_indicator($("#admin_page_invites_loading_indicator"));
diff --git a/static/js/setup.js b/static/js/setup.js
index 55afa8980f..79d0a5f892 100644
--- a/static/js/setup.js
+++ b/static/js/setup.js
@@ -64,12 +64,10 @@ $(() => {
         }
     });
 
-    if (typeof $ !== "undefined") {
-        $.fn.expectOne = function () {
-            if (blueslip && this.length !== 1) {
-                blueslip.error("Expected one element in jQuery set, " + this.length + " found");
-            }
-            return this;
-        };
-    }
+    $.fn.expectOne = function () {
+        if (blueslip && this.length !== 1) {
+            blueslip.error("Expected one element in jQuery set, " + this.length + " found");
+        }
+        return this;
+    };
 });
diff --git a/static/js/stream_data.js b/static/js/stream_data.js
index c9890b75db..b95a37d366 100644
--- a/static/js/stream_data.js
+++ b/static/js/stream_data.js
@@ -679,7 +679,7 @@ export function maybe_get_stream_name(stream_id) {
 
 export function is_user_subscribed(stream_id, user_id) {
     const sub = get_sub_by_id(stream_id);
-    if (typeof sub === "undefined" || !sub.can_access_subscribers) {
+    if (sub === undefined || !sub.can_access_subscribers) {
         // If we don't know about the stream, or we ourselves cannot access subscriber list,
         // so we return undefined (treated as falsy if not explicitly handled).
         blueslip.warn(
@@ -687,7 +687,7 @@ export function is_user_subscribed(stream_id, user_id) {
         );
         return undefined;
     }
-    if (typeof user_id === "undefined") {
+    if (user_id === undefined) {
         blueslip.warn("Undefined user_id passed to function is_user_subscribed");
         return undefined;
     }
diff --git a/static/js/subs.js b/static/js/subs.js
index 70db24a62d..5667abd7e4 100644
--- a/static/js/subs.js
+++ b/static/js/subs.js
@@ -111,7 +111,7 @@ export function get_active_data() {
 }
 
 function get_hash_safe() {
-    if (typeof window !== "undefined" && typeof window.location.hash === "string") {
+    if (typeof window.location.hash === "string") {
         return window.location.hash.slice(1);
     }
 
diff --git a/static/js/timerender.js b/static/js/timerender.js
index 2e967aedfc..dfef666102 100644
--- a/static/js/timerender.js
+++ b/static/js/timerender.js
@@ -286,10 +286,7 @@ export const absolute_time = (function () {
         return str;
     };
 
-    return function (timestamp, today) {
-        if (typeof today === "undefined") {
-            today = new Date();
-        }
+    return function (timestamp, today = new Date()) {
         const date = new Date(timestamp);
         const is_older_year = today.getFullYear() - date.getFullYear() > 0;
         const H_24 = page_params.twenty_four_hour_time;
diff --git a/static/js/ui_util.js b/static/js/ui_util.js
index b9c282f535..6047c7b229 100644
--- a/static/js/ui_util.js
+++ b/static/js/ui_util.js
@@ -11,14 +11,14 @@ export function change_tab_to(tabname) {
 export function place_caret_at_end(el) {
     el.focus();
 
-    if (typeof window.getSelection !== "undefined" && typeof document.createRange !== "undefined") {
+    if (window.getSelection !== undefined && document.createRange !== undefined) {
         const range = document.createRange();
         range.selectNodeContents(el);
         range.collapse(false);
         const sel = window.getSelection();
         sel.removeAllRanges();
         sel.addRange(range);
-    } else if (typeof document.body.createTextRange !== "undefined") {
+    } else if (document.body.createTextRange !== undefined) {
         const textRange = document.body.createTextRange();
         textRange.moveToElementText(el);
         textRange.collapse(false);