diff --git a/frontend/src/js/controllers/account-controller.js b/frontend/src/js/controllers/account-controller.js
index b24ac3cf8..88a77a5ef 100644
--- a/frontend/src/js/controllers/account-controller.js
+++ b/frontend/src/js/controllers/account-controller.js
@@ -555,7 +555,7 @@ export async function addPasswordAuth(email, password) {
       return Notifications.add("Could not reauthenticate: " + e.message, -1);
     }
   }
-  var credential = firebase.auth.EmailAuthProvider.credential(email, password);
+  let credential = firebase.auth.EmailAuthProvider.credential(email, password);
   firebase
     .auth()
     .currentUser.linkWithCredential(credential)
diff --git a/frontend/src/js/controllers/chart-controller.js b/frontend/src/js/controllers/chart-controller.js
index 540233958..a671159db 100644
--- a/frontend/src/js/controllers/chart-controller.js
+++ b/frontend/src/js/controllers/chart-controller.js
@@ -40,13 +40,13 @@ export let result = new Chart($("#wpmChart"), {
         type: "scatter",
         pointStyle: "crossRot",
         radius: function (context) {
-          var index = context.dataIndex;
-          var value = context.dataset.data[index];
+          let index = context.dataIndex;
+          let value = context.dataset.data[index];
           return value <= 0 ? 0 : 3;
         },
         pointHoverRadius: function (context) {
-          var index = context.dataIndex;
-          var value = context.dataset.data[index];
+          let index = context.dataIndex;
+          let value = context.dataset.data[index];
           return value <= 0 ? 0 : 5;
         },
       },
@@ -487,13 +487,13 @@ export let miniResult = new Chart($(".pageAccount #miniResultChart"), {
         type: "scatter",
         pointStyle: "crossRot",
         radius: function (context) {
-          var index = context.dataIndex;
-          var value = context.dataset.data[index];
+          let index = context.dataIndex;
+          let value = context.dataset.data[index];
           return value <= 0 ? 0 : 3;
         },
         pointHoverRadius: function (context) {
-          var index = context.dataIndex;
-          var value = context.dataset.data[index];
+          let index = context.dataIndex;
+          let value = context.dataset.data[index];
           return value <= 0 ? 0 : 5;
         },
       },
diff --git a/frontend/src/js/controllers/input-controller.js b/frontend/src/js/controllers/input-controller.js
index 0d9df23a2..98d4294b7 100644
--- a/frontend/src/js/controllers/input-controller.js
+++ b/frontend/src/js/controllers/input-controller.js
@@ -587,8 +587,8 @@ function handleTab(event) {
 
     let area = $("#customTextPopup .textarea")[0];
 
-    var start = area.selectionStart;
-    var end = area.selectionEnd;
+    let start = area.selectionStart;
+    let end = area.selectionEnd;
 
     // set textarea value to: text before caret + tab + text after caret
     area.value =
diff --git a/frontend/src/js/controllers/route-controller.js b/frontend/src/js/controllers/route-controller.js
index c125d3219..8cc175d36 100644
--- a/frontend/src/js/controllers/route-controller.js
+++ b/frontend/src/js/controllers/route-controller.js
@@ -25,7 +25,7 @@ export function handleInitialPageClasses(pathname) {
 }
 
 (function (history) {
-  var pushState = history.pushState;
+  let pushState = history.pushState;
   history.pushState = function (state) {
     if (Config.funbox === "memory" && state !== "/") {
       Funbox.resetMemoryTimer();
diff --git a/frontend/src/js/controllers/theme-controller.js b/frontend/src/js/controllers/theme-controller.js
index c5429b116..3f10bcc8a 100644
--- a/frontend/src/js/controllers/theme-controller.js
+++ b/frontend/src/js/controllers/theme-controller.js
@@ -35,7 +35,7 @@ function updateFavicon(size, curveSize) {
       bgcolor = "#111";
       maincolor = "#eee";
     }
-    var canvas = document.createElement("canvas");
+    let canvas = document.createElement("canvas");
     canvas.width = size;
     canvas.height = size;
     let ctx = canvas.getContext("2d");
@@ -159,7 +159,7 @@ export function clearPreview() {
 }
 
 export function randomizeTheme() {
-  var randomList;
+  let randomList;
   Misc.getThemesList().then((themes) => {
     if (Config.randomTheme === "fav" && Config.favThemes.length > 0) {
       randomList = Config.favThemes;
diff --git a/frontend/src/js/db.js b/frontend/src/js/db.js
index 0c0e92e69..4f97987e0 100644
--- a/frontend/src/js/db.js
+++ b/frontend/src/js/db.js
@@ -314,7 +314,7 @@ export async function getUserAverageWpm10(
   let retval = 0;
 
   if (dbSnapshot == null) return retval;
-  var dbSnapshotValid = await getUserResults();
+  let dbSnapshotValid = await getUserResults();
   if (dbSnapshotValid === false) {
     return retval;
   }
diff --git a/frontend/src/js/elements/keymap.js b/frontend/src/js/elements/keymap.js
index f0f5d42e9..0ad717455 100644
--- a/frontend/src/js/elements/keymap.js
+++ b/frontend/src/js/elements/keymap.js
@@ -192,14 +192,14 @@ export function refreshKeys(layout) {
       $(".keymap .r4 .keymap-key.first").addClass("hidden-key");
     }
 
-    var toReplace = lts.keys.slice(1, 48);
-    var count = 0;
+    let toReplace = lts.keys.slice(1, 48);
+    let count = 0;
 
     // let repeatB = false;
     $(".keymap .keymap-key .letter")
       .map(function () {
         if (count < toReplace.length) {
-          var key = toReplace[count].charAt(0);
+          let key = toReplace[count].charAt(0);
           this.innerHTML = key;
 
           switch (key) {
diff --git a/frontend/src/js/settings/theme-picker.js b/frontend/src/js/settings/theme-picker.js
index c5aadfc91..360a64a9a 100644
--- a/frontend/src/js/settings/theme-picker.js
+++ b/frontend/src/js/settings/theme-picker.js
@@ -193,7 +193,7 @@ export function updateActiveTab() {
 
 $(".pageSettings .section.themes .tabs .button").click((e) => {
   $(".pageSettings .section.themes .tabs .button").removeClass("active");
-  var $target = $(e.currentTarget);
+  let $target = $(e.currentTarget);
   $target.addClass("active");
   setCustomInputs();
   if ($target.attr("tab") == "preset") {
diff --git a/frontend/src/js/test/poetry.js b/frontend/src/js/test/poetry.js
index 4fe4640f4..802a0f0c8 100644
--- a/frontend/src/js/test/poetry.js
+++ b/frontend/src/js/test/poetry.js
@@ -12,11 +12,11 @@ export class Poem {
   }
 
   cleanUpText() {
-    var count = 0;
-    var scrubbedWords = [];
-    for (var i = 0; i < this.words.length; i++) {
+    let count = 0;
+    let scrubbedWords = [];
+    for (let i = 0; i < this.words.length; i++) {
       let scrubbed = "";
-      for (var j = 0; j < this.words[i].length; j++) {
+      for (let j = 0; j < this.words[i].length; j++) {
         if (!bannedChars.includes(this.words[i][j]))
           scrubbed += this.words[i][j];
       }
@@ -36,7 +36,7 @@ export class Poem {
 export async function getPoem() {
   return new Promise((res, rej) => {
     console.log("Getting poem");
-    var poemReq = new XMLHttpRequest();
+    let poemReq = new XMLHttpRequest();
     poemReq.onload = () => {
       if (poemReq.readyState == 4) {
         if (poemReq.status == 200) {
diff --git a/frontend/src/js/test/test-logic.js b/frontend/src/js/test/test-logic.js
index 8ea9a4bda..fc1f1accd 100644
--- a/frontend/src/js/test/test-logic.js
+++ b/frontend/src/js/test/test-logic.js
@@ -1043,7 +1043,7 @@ export async function addWord() {
   }
 }
 
-var retrySaving = {
+let retrySaving = {
   completedEvent: null,
   canRetry: false,
 };
@@ -1067,7 +1067,7 @@ export function retrySavingResult() {
 
   Notifications.add("Retrying to save...");
 
-  var { completedEvent } = retrySaving;
+  let { completedEvent } = retrySaving;
 
   axiosInstance
     .post("/results/add", {
diff --git a/frontend/src/js/test/test-ui.js b/frontend/src/js/test/test-ui.js
index 42e79d6b0..ab2d79004 100644
--- a/frontend/src/js/test/test-ui.js
+++ b/frontend/src/js/test/test-ui.js
@@ -231,12 +231,12 @@ export async function screenshot() {
   }
   $(".pageTest .buttons").addClass("hidden");
   let src = $("#middle");
-  var sourceX = src.position().left; /*X position from div#target*/
-  var sourceY = src.position().top; /*Y position from div#target*/
-  var sourceWidth = src.outerWidth(
+  let sourceX = src.position().left; /*X position from div#target*/
+  let sourceY = src.position().top; /*Y position from div#target*/
+  let sourceWidth = src.outerWidth(
     true
   ); /*clientWidth/offsetWidth from div#target*/
-  var sourceHeight = src.outerHeight(
+  let sourceHeight = src.outerHeight(
     true
   ); /*clientHeight/offsetHeight from div#target*/
   $("#notificationCenter").addClass("hidden");
diff --git a/frontend/src/js/test/wikipedia.js b/frontend/src/js/test/wikipedia.js
index b2d92bee3..ee5316cd8 100644
--- a/frontend/src/js/test/wikipedia.js
+++ b/frontend/src/js/test/wikipedia.js
@@ -48,9 +48,9 @@ export async function getSection(language) {
   urlTLD = await getTLD(currentLanguageGroup);
 
   const randomPostURL = `https://${urlTLD}.wikipedia.org/api/rest_v1/page/random/summary`;
-  var sectionObj = {};
-  var randomPostReq = await fetch(randomPostURL);
-  var pageid = 0;
+  let sectionObj = {};
+  let randomPostReq = await fetch(randomPostURL);
+  let pageid = 0;
 
   if (randomPostReq.status == 200) {
     let postObj = await randomPostReq.json();
@@ -67,7 +67,7 @@ export async function getSection(language) {
 
     const sectionURL = `https://${urlTLD}.wikipedia.org/w/api.php?action=query&format=json&pageids=${pageid}&prop=extracts&exintro=true&origin=*`;
 
-    var sectionReq = new XMLHttpRequest();
+    let sectionReq = new XMLHttpRequest();
     sectionReq.onload = () => {
       if (sectionReq.readyState == 4) {
         if (sectionReq.status == 200) {