diff --git a/binaries/data/mods/public/gui/replaymenu/replay_actions.js b/binaries/data/mods/public/gui/replaymenu/replay_actions.js
index 0d9046ab42..be3a701b4d 100644
--- a/binaries/data/mods/public/gui/replaymenu/replay_actions.js
+++ b/binaries/data/mods/public/gui/replaymenu/replay_actions.js
@@ -3,17 +3,17 @@
  */
 function createReplaySelectionData(selectedDirectory)
 {
-	let replaySelection = Engine.GetGUIObjectByName("replaySelection");
-	let dateTimeFilter = Engine.GetGUIObjectByName("dateTimeFilter");
-	let playersFilter = Engine.GetGUIObjectByName("playersFilter");
-	let mapNameFilter = Engine.GetGUIObjectByName("mapNameFilter");
-	let mapSizeFilter = Engine.GetGUIObjectByName("mapSizeFilter");
-	let populationFilter = Engine.GetGUIObjectByName("populationFilter");
-	let durationFilter = Engine.GetGUIObjectByName("durationFilter");
-	let compatibilityFilter = Engine.GetGUIObjectByName("compatibilityFilter");
-	let singleplayerFilter = Engine.GetGUIObjectByName("singleplayerFilter");
-	let victoryConFilter = Engine.GetGUIObjectByName("victoryConditionFilter");
-	let ratedGamesFilter = Engine.GetGUIObjectByName("ratedGamesFilter");
+	const replaySelection = Engine.GetGUIObjectByName("replaySelection");
+	const dateTimeFilter = Engine.GetGUIObjectByName("dateTimeFilter");
+	const playersFilter = Engine.GetGUIObjectByName("playersFilter");
+	const mapNameFilter = Engine.GetGUIObjectByName("mapNameFilter");
+	const mapSizeFilter = Engine.GetGUIObjectByName("mapSizeFilter");
+	const populationFilter = Engine.GetGUIObjectByName("populationFilter");
+	const durationFilter = Engine.GetGUIObjectByName("durationFilter");
+	const compatibilityFilter = Engine.GetGUIObjectByName("compatibilityFilter");
+	const singleplayerFilter = Engine.GetGUIObjectByName("singleplayerFilter");
+	const victoryConFilter = Engine.GetGUIObjectByName("victoryConditionFilter");
+	const ratedGamesFilter = Engine.GetGUIObjectByName("ratedGamesFilter");
 
 	return {
 		"directory": selectedDirectory,
@@ -86,7 +86,7 @@ function displayReplayCompatibilityError(replay)
 	var errMsg;
 	if (replayHasSameEngineVersion(replay))
 	{
-		let gameMods = replay.attribs.mods || [];
+		const gameMods = replay.attribs.mods || [];
 		errMsg = translate("This replay needs a different sequence of mods:") + "\n" +
 			comparedModsString(gameMods, g_EngineInfo.mods);
 	}
@@ -105,11 +105,11 @@ function displayReplayCompatibilityError(replay)
  */
 function showReplaySummary()
 {
-	let selected = Engine.GetGUIObjectByName("replaySelection").selected;
+	const selected = Engine.GetGUIObjectByName("replaySelection").selected;
 	if (selected == -1)
 		return;
 
-	let replay = g_ReplaysFiltered[selected];
+	const replay = g_ReplaysFiltered[selected];
 	if (isReplayCompatible(replay))
 		reallyShowReplaySummary(replay.directory);
 	else
@@ -119,7 +119,7 @@ function showReplaySummary()
 function reallyShowReplaySummary(directory)
 {
 	// Load summary screen data from the selected replay directory
-	let simData = Engine.GetReplayMetadata(directory);
+	const simData = Engine.GetReplayMetadata(directory);
 
 	if (!simData)
 	{
@@ -141,7 +141,7 @@ function reallyShowReplaySummary(directory)
 
 function reloadCache()
 {
-	let selected = Engine.GetGUIObjectByName("replaySelection").selected;
+	const selected = Engine.GetGUIObjectByName("replaySelection").selected;
 	loadReplays(selected > -1 ? createReplaySelectionData(g_ReplaysFiltered[selected].directory) : "", true);
 }
 
diff --git a/binaries/data/mods/public/gui/replaymenu/replay_filters.js b/binaries/data/mods/public/gui/replaymenu/replay_filters.js
index 0a13d9b482..85ba489ef9 100644
--- a/binaries/data/mods/public/gui/replaymenu/replay_filters.js
+++ b/binaries/data/mods/public/gui/replaymenu/replay_filters.js
@@ -151,7 +151,7 @@ function initDurationFilter(filters)
 
 function initSingleplayerFilter(filters)
 {
-	let singleplayerFilter = Engine.GetGUIObjectByName("singleplayerFilter");
+	const singleplayerFilter = Engine.GetGUIObjectByName("singleplayerFilter");
 	singleplayerFilter.list = [
 		translateWithContext("replay filter", "Any"),
 		translateWithContext("replay filter", "Single-player"),
@@ -169,7 +169,7 @@ function initSingleplayerFilter(filters)
 
 function initVictoryConditionFilter(filters)
 {
-	let victoryConditionFilter = Engine.GetGUIObjectByName("victoryConditionFilter");
+	const victoryConditionFilter = Engine.GetGUIObjectByName("victoryConditionFilter");
 	victoryConditionFilter.list = [translate("Any victory condition")].concat(g_VictoryConditions.map(victoryCondition => translateVictoryCondition(victoryCondition.Name)));
 	victoryConditionFilter.list_data = [""].concat(g_VictoryConditions.map(victoryCondition => victoryCondition.Name));
 
@@ -182,7 +182,7 @@ function initVictoryConditionFilter(filters)
 
 function initRatedGamesFilter(filters)
 {
-	let ratedGamesFilter = Engine.GetGUIObjectByName("ratedGamesFilter");
+	const ratedGamesFilter = Engine.GetGUIObjectByName("ratedGamesFilter");
 	ratedGamesFilter.list = [translate("Rated and unrated games"), translate("Rated games"), translate("Unrated games")];
 	ratedGamesFilter.list_data = ["", "rated", "not rated"];
 
@@ -198,8 +198,8 @@ function initRatedGamesFilter(filters)
  */
 function filterReplays()
 {
-	let sortKey = Engine.GetGUIObjectByName("replaySelection").selected_column;
-	let sortOrder = Engine.GetGUIObjectByName("replaySelection").selected_column_order;
+	const sortKey = Engine.GetGUIObjectByName("replaySelection").selected_column;
+	const sortOrder = Engine.GetGUIObjectByName("replaySelection").selected_column_order;
 
 	g_ReplaysFiltered = g_Replays.filter(replay => filterReplay(replay)).sort((a, b) => {
 		let cmpA, cmpB, cmpA_secondary, cmpB_secondary;
@@ -256,67 +256,67 @@ function filterReplays()
 function filterReplay(replay)
 {
 	// Check for compatibility first (most likely to filter)
-	let compatibilityFilter = Engine.GetGUIObjectByName("compatibilityFilter");
+	const compatibilityFilter = Engine.GetGUIObjectByName("compatibilityFilter");
 	if (compatibilityFilter.checked && !isReplayCompatible(replay))
 		return false;
 
 	// Filter by single-player or multiplayer.
-	let singleplayerFilter = Engine.GetGUIObjectByName("singleplayerFilter");
-	let selectedSingleplayerFilter = singleplayerFilter.list_data[singleplayerFilter.selected] || "";
+	const singleplayerFilter = Engine.GetGUIObjectByName("singleplayerFilter");
+	const selectedSingleplayerFilter = singleplayerFilter.list_data[singleplayerFilter.selected] || "";
 	if (selectedSingleplayerFilter == "Campaigns" && !replay.isCampaign ||
 	    selectedSingleplayerFilter == "Single-player" && (replay.isMultiplayer || replay.isCampaign) ||
 	    selectedSingleplayerFilter == "Multiplayer" && (!replay.isMultiplayer || replay.isCampaign))
 		return false;
 
 	// Filter by victory condition
-	let victoryConditionFilter = Engine.GetGUIObjectByName("victoryConditionFilter");
+	const victoryConditionFilter = Engine.GetGUIObjectByName("victoryConditionFilter");
 	if (victoryConditionFilter.selected > 0 &&
 	    replay.attribs.settings.VictoryConditions.indexOf(victoryConditionFilter.list_data[victoryConditionFilter.selected]) == -1)
 		return false;
 
 	// Filter by rating
-	let ratedGamesFilter = Engine.GetGUIObjectByName("ratedGamesFilter");
-	let selectedRatedGamesFilter = ratedGamesFilter.list_data[ratedGamesFilter.selected] || "";
+	const ratedGamesFilter = Engine.GetGUIObjectByName("ratedGamesFilter");
+	const selectedRatedGamesFilter = ratedGamesFilter.list_data[ratedGamesFilter.selected] || "";
 	if (selectedRatedGamesFilter == "rated" && !replay.isRated ||
 	    selectedRatedGamesFilter == "not rated" && replay.isRated)
 		return false;
 
 	// Filter date/time (select a month)
-	let dateTimeFilter = Engine.GetGUIObjectByName("dateTimeFilter");
+	const dateTimeFilter = Engine.GetGUIObjectByName("dateTimeFilter");
 	if (dateTimeFilter.selected > 0 && getReplayMonth(replay) != dateTimeFilter.list_data[dateTimeFilter.selected])
 		return false;
 
 	// Filter by playernames
-	let playersFilter = Engine.GetGUIObjectByName("playersFilter");
-	let keywords = playersFilter.caption.toLowerCase().split(" ");
+	const playersFilter = Engine.GetGUIObjectByName("playersFilter");
+	const keywords = playersFilter.caption.toLowerCase().split(" ");
 	if (keywords.length)
 	{
 		// We just check if all typed words are somewhere in the playerlist of that replay
-		let playerList = replay.attribs.settings.PlayerData.map(player => player ? player.Name : "").join(" ").toLowerCase();
+		const playerList = replay.attribs.settings.PlayerData.map(player => player ? player.Name : "").join(" ").toLowerCase();
 		if (!keywords.every(keyword => playerList.indexOf(keyword) != -1))
 			return false;
 	}
 
 	// Filter by map name
-	let mapNameFilter = Engine.GetGUIObjectByName("mapNameFilter");
+	const mapNameFilter = Engine.GetGUIObjectByName("mapNameFilter");
 	if (mapNameFilter.selected > 0 && replay.attribs.settings.mapName != mapNameFilter.list_data[mapNameFilter.selected])
 		return false;
 
 	// Filter by map size
-	let mapSizeFilter = Engine.GetGUIObjectByName("mapSizeFilter");
+	const mapSizeFilter = Engine.GetGUIObjectByName("mapSizeFilter");
 	if (mapSizeFilter.selected > 0 && replay.attribs.settings.Size != mapSizeFilter.list_data[mapSizeFilter.selected])
 		return false;
 
 	// Filter by population capacity
-	let populationFilter = Engine.GetGUIObjectByName("populationFilter");
+	const populationFilter = Engine.GetGUIObjectByName("populationFilter");
 	if (populationFilter.selected > 0 && replay.attribs.settings.PopulationCap != populationFilter.list_data[populationFilter.selected])
 		return false;
 
 	// Filter by game duration
-	let durationFilter = Engine.GetGUIObjectByName("durationFilter");
+	const durationFilter = Engine.GetGUIObjectByName("durationFilter");
 	if (durationFilter.selected > 0)
 	{
-		let interval = g_DurationFilterIntervals[durationFilter.selected];
+		const interval = g_DurationFilterIntervals[durationFilter.selected];
 
 		if ((interval.min > -1 && replay.duration < interval.min * 60) ||
 			(interval.max > -1 && replay.duration > interval.max * 60))
diff --git a/binaries/data/mods/public/gui/replaymenu/replay_menu.js b/binaries/data/mods/public/gui/replaymenu/replay_menu.js
index 080ce132a3..f13193c2cd 100644
--- a/binaries/data/mods/public/gui/replaymenu/replay_menu.js
+++ b/binaries/data/mods/public/gui/replaymenu/replay_menu.js
@@ -96,7 +96,7 @@ function loadReplays(replaySelectionData, compareFiles)
 		return;
 
 	g_Playernames = [];
-	for (let replay of g_Replays)
+	for (const replay of g_Replays)
 	{
 		let nonAIPlayers = 0;
 
@@ -110,14 +110,14 @@ function loadReplays(replaySelectionData, compareFiles)
 			g_MapNames.push(replay.attribs.settings.mapName);
 
 		// Extract playernames
-		for (let playerData of replay.attribs.settings.PlayerData)
+		for (const playerData of replay.attribs.settings.PlayerData)
 		{
 			if (!playerData || playerData.AI)
 				continue;
 
 			// Remove rating from nick
 			let playername = playerData.Name;
-			let ratingStart = playername.indexOf(" (");
+			const ratingStart = playername.indexOf(" (");
 			if (ratingStart != -1)
 				playername = playername.substr(0, ratingStart);
 
@@ -147,7 +147,7 @@ function loadReplays(replaySelectionData, compareFiles)
 		if (replaySelectionData.directory)
 			g_SelectedReplayDirectory = replaySelectionData.directory;
 
-		let replaySelection = Engine.GetGUIObjectByName("replaySelection");
+		const replaySelection = Engine.GetGUIObjectByName("replaySelection");
 		if (replaySelectionData.column)
 			replaySelection.selected_column = replaySelectionData.column;
 		if (replaySelectionData.columnOrder)
@@ -230,7 +230,7 @@ function displayReplayList()
 	filterReplays();
 
 	var list = g_ReplaysFiltered.map(replay => {
-		let works = replay.isCompatible;
+		const works = replay.isCompatible;
 		return {
 			"directories": replay.directory,
 			"months": compatibilityColor(getReplayDateTime(replay), works),
@@ -268,8 +268,8 @@ function displayReplayList()
  */
 function displayReplayDetails()
 {
-	let selected = Engine.GetGUIObjectByName("replaySelection").selected;
-	let replaySelected = selected > -1;
+	const selected = Engine.GetGUIObjectByName("replaySelection").selected;
+	const replaySelected = selected > -1;
 
 	Engine.GetGUIObjectByName("replayInfo").hidden = !replaySelected;
 	Engine.GetGUIObjectByName("replayInfoEmpty").hidden = replaySelected;
@@ -281,7 +281,7 @@ function displayReplayDetails()
 	if (!replaySelected)
 		return;
 
-	let replay = g_ReplaysFiltered[selected];
+	const replay = g_ReplaysFiltered[selected];
 
 	Engine.GetGUIObjectByName("sgMapName").caption = translate(replay.attribs.settings.mapName);
 	Engine.GetGUIObjectByName("sgMapSize").caption = translateMapSize(replay.attribs.settings.Size);
@@ -292,7 +292,7 @@ function displayReplayDetails()
 		{ "numberOfPlayers": replay.attribs.settings.PlayerData.length });
 	Engine.GetGUIObjectByName("replayFilename").caption = Engine.GetReplayDirectoryName(replay.directory);
 
-	let metadata = Engine.GetReplayMetadata(replay.directory);
+	const metadata = Engine.GetReplayMetadata(replay.directory);
 	Engine.GetGUIObjectByName("sgPlayersNames").caption =
 		formatPlayerInfo(
 			replay.attribs.settings.PlayerData,
diff --git a/binaries/data/mods/public/gui/splashscreen/splashscreen.js b/binaries/data/mods/public/gui/splashscreen/splashscreen.js
index a961474d50..8c6c71573a 100644
--- a/binaries/data/mods/public/gui/splashscreen/splashscreen.js
+++ b/binaries/data/mods/public/gui/splashscreen/splashscreen.js
@@ -8,13 +8,13 @@ async function init(data)
 	const paragraphSpacing = 20;
 	let verticalOffset = paragraphSpacing * 3;
 
-	for (let paragraphObject of paragraphObjects)
+	for (const paragraphObject of paragraphObjects)
 	{
 		const text = paragraphObject.children.find(object => object.toString().startsWith("text"));
 		const icon = paragraphObject.children.find(object => object.toString().startsWith("icon"));
 
 		text.size = new GUISize(textIndent, verticalOffset, -10, 0, 0, 0, 100, 100);
-		let paragraphHeight = Math.max(text.getTextSize().height, iconSize);
+		const paragraphHeight = Math.max(text.getTextSize().height, iconSize);
 		const sizeTop = Math.min(verticalOffset + 5, verticalOffset + paragraphHeight / 2 - iconSize / 2);
 		icon.size = new GUISize(
 			iconMargin, sizeTop,
diff --git a/binaries/data/mods/public/gui/summary/counters.js b/binaries/data/mods/public/gui/summary/counters.js
index 457f22d4c1..83cb4c57d3 100644
--- a/binaries/data/mods/public/gui/summary/counters.js
+++ b/binaries/data/mods/public/gui/summary/counters.js
@@ -16,7 +16,7 @@ function formatSummaryValue(values)
 		return values === Infinity ? g_InfinitySymbol : values;
 
 	let ret = "";
-	for (let type in values)
+	for (const type in values)
 		if (!g_SummaryTypes[type].hideInSummary)
 			ret += (g_SummaryTypes[type].color ?
 				coloredText(values[type], g_SummaryTypes[type].color) :
@@ -26,17 +26,17 @@ function formatSummaryValue(values)
 
 function getPlayerValuesPerTeam(team, index, type, counters, headings)
 {
-	let fn = counters[headings.map(heading => heading.identifier).indexOf(type) - 1].fn;
+	const fn = counters[headings.map(heading => heading.identifier).indexOf(type) - 1].fn;
 	return g_Teams[team].map(player => fn(g_GameData.sim.playerStates[player], index, type));
 }
 
 function updateCountersPlayer(playerState, allCounters, allHeadings, idGUI, index)
 {
-	let counters = allCounters.filter(counter => !counter.hideInSummary);
-	let headings = allHeadings.filter(heading => !heading.hideInSummary);
-	for (let n in counters)
+	const counters = allCounters.filter(counter => !counter.hideInSummary);
+	const headings = allHeadings.filter(heading => !heading.hideInSummary);
+	for (const n in counters)
 	{
-		let fn = counters[n].fn;
+		const fn = counters[n].fn;
 		Engine.GetGUIObjectByName(idGUI + "[" + n + "]").caption =
 			formatSummaryValue(fn && fn(playerState, index, headings[+n + 1].identifier));
 	}
@@ -44,14 +44,14 @@ function updateCountersPlayer(playerState, allCounters, allHeadings, idGUI, inde
 
 function updateCountersTeam(teamFn, allCounters, allHeadings, index)
 {
-	let counters = allCounters.filter(counter => !counter.hideInSummary);
-	let headings = allHeadings.filter(heading => !heading.hideInSummary);
-	for (let team in g_Teams)
+	const counters = allCounters.filter(counter => !counter.hideInSummary);
+	const headings = allHeadings.filter(heading => !heading.hideInSummary);
+	for (const team in g_Teams)
 	{
 		if (team == -1)
 			continue;
 
-		for (let n in counters)
+		for (const n in counters)
 			Engine.GetGUIObjectByName("valueDataTeam[" + team + "][" + n + "]").caption =
 				formatSummaryValue(teamFn(team, index, headings[+n + 1].identifier, counters, headings));
 	}
@@ -67,7 +67,7 @@ function updateCountersTeam(teamFn, allCounters, allHeadings, index)
  */
 function summaryAddObject(obj1, obj2)
 {
-	for (let p in obj1)
+	for (const p in obj1)
 		obj1[p] += obj2[p];
 }
 
@@ -92,12 +92,12 @@ function calculateTeamCounterDataHelper()
 {
 	for (let i = 0; i < g_PlayerCount; ++i)
 	{
-		let playerState = g_GameData.sim.playerStates[i + 1];
+		const playerState = g_GameData.sim.playerStates[i + 1];
 
 		if (!g_TeamHelperData[playerState.team])
 		{
 			g_TeamHelperData[playerState.team] = {};
-			for (let value of ["food", "vegetarianFood", "femaleCitizen", "worker", "enemyUnitsKilled",
+			for (const value of ["food", "vegetarianFood", "femaleCitizen", "worker", "enemyUnitsKilled",
 			                   "unitsLost", "mapControl", "mapControlPeak",
 			                   "mapExploration", "totalBought", "totalSold"])
 				g_TeamHelperData[playerState.team][value] = new Array(playerState.sequences.time.length).fill(0);
@@ -117,10 +117,10 @@ function calculateTeamCounterDataHelper()
 
 		g_TeamHelperData[playerState.team].mapExploration = playerState.sequences.teamPercentMapExplored;
 
-		for (let type in playerState.sequences.resourcesBought)
+		for (const type in playerState.sequences.resourcesBought)
 			summaryAddObject(g_TeamHelperData[playerState.team].totalBought, playerState.sequences.resourcesBought[type]);
 
-		for (let type in playerState.sequences.resourcesSold)
+		for (const type in playerState.sequences.resourcesSold)
 			summaryAddObject(g_TeamHelperData[playerState.team].totalSold, playerState.sequences.resourcesSold[type]);
 	}
 }
@@ -133,7 +133,7 @@ function calculateEconomyScore(playerState, index)
 	let total = 0;
 
 	// Notice that this skips the vegetarianFood property of resourcesGathered
-	for (let type of g_ResourceData.GetCodes())
+	for (const type of g_ResourceData.GetCodes())
 		total += playerState.sequences.resourcesGathered[type][index];
 
 	total += playerState.sequences.tradeIncome[index];
@@ -235,7 +235,7 @@ function calculateTotalResources(playerState, index)
 	let totalUsed = 0;
 	let totalCount = 0;
 
-	for (let type of g_ResourceData.GetCodes())
+	for (const type of g_ResourceData.GetCodes())
 	{
 		totalCount += playerState.sequences.resourcesCount[type][index];
 		totalGathered += playerState.sequences.resourcesGathered[type][index];
@@ -286,10 +286,10 @@ function calculateBarterEfficiency(playerState, index)
 	let totalBought = 0;
 	let totalSold = 0;
 
-	for (let type in playerState.sequences.resourcesBought)
+	for (const type in playerState.sequences.resourcesBought)
 		totalBought += playerState.sequences.resourcesBought[type][index];
 
-	for (let type in playerState.sequences.resourcesSold)
+	for (const type in playerState.sequences.resourcesSold)
 		totalSold += playerState.sequences.resourcesSold[type][index];
 
 	return calculatePercent(totalBought, totalSold);
diff --git a/binaries/data/mods/public/gui/summary/layout.js b/binaries/data/mods/public/gui/summary/layout.js
index aeefdbe459..ff0d26c99c 100644
--- a/binaries/data/mods/public/gui/summary/layout.js
+++ b/binaries/data/mods/public/gui/summary/layout.js
@@ -256,16 +256,16 @@ function resetGeneralPanel()
 
 function updateGeneralPanelHeadings(allHeadings)
 {
-	let headings = allHeadings.filter(heading => !heading.hideInSummary);
+	const headings = allHeadings.filter(heading => !heading.hideInSummary);
 
 	let left = 50;
-	for (let h in headings)
+	for (const h in headings)
 	{
 		let headerGUIName = "playerNameHeading";
 		if (h > 0)
 			headerGUIName = "Heading[" + (h - 1) + "]";
 
-		let headerGUI = Engine.GetGUIObjectByName(headerGUIName);
+		const headerGUI = Engine.GetGUIObjectByName(headerGUIName);
 		headerGUI.caption = headings[h].headerCaption || headings[h].caption;
 		headerGUI.size = (left - 4) + " " + headings[h].yStart + " " + (left + headings[h].width + 4) + " 69";
 		headerGUI.hidden = false;
@@ -278,7 +278,7 @@ function updateGeneralPanelHeadings(allHeadings)
 function updateGeneralPanelTitles(titleHeadings)
 {
 	let left = 250;
-	for (let th in titleHeadings)
+	for (const th in titleHeadings)
 	{
 		if (th >= g_MaxHeadingTitle)
 			break;
@@ -286,7 +286,7 @@ function updateGeneralPanelTitles(titleHeadings)
 		if (titleHeadings[th].xOffset)
 			left += titleHeadings[th].xOffset;
 
-		let headerGUI = Engine.GetGUIObjectByName("titleHeading[" + th + "]");
+		const headerGUI = Engine.GetGUIObjectByName("titleHeading[" + th + "]");
 		headerGUI.caption = titleHeadings[th].caption;
 		headerGUI.size = left + " " + titleHeadings[th].yStart + " " + (left + titleHeadings[th].width) + " 100%";
 		headerGUI.hidden = false;
@@ -298,7 +298,7 @@ function updateGeneralPanelTitles(titleHeadings)
 
 function updateGeneralPanelCounter(allCounters)
 {
-	let counters = allCounters.filter(counter => !counter.hideInSummary);
+	const counters = allCounters.filter(counter => !counter.hideInSummary);
 	let rowPlayerObjectWidth = 0;
 	let left = 0;
 
@@ -307,7 +307,7 @@ function updateGeneralPanelCounter(allCounters)
 		left = 240;
 		let counterObject;
 
-		for (let w in counters)
+		for (const w in counters)
 		{
 			counterObject = Engine.GetGUIObjectByName("valueData[" + p + "][" + w + "]");
 			counterObject.size = left + " 0 " + (left + counters[w].width) + " 100%";
@@ -322,7 +322,7 @@ function updateGeneralPanelCounter(allCounters)
 		for (let t = 0; t < g_MaxTeams; ++t)
 		{
 			left = 240;
-			for (let w in counters)
+			for (const w in counters)
 			{
 				counterObject = Engine.GetGUIObjectByName("valueDataTeam[" + t + "][" + p + "][" + w + "]");
 				counterObject.size = left + " 0 " + (left + counters[w].width) + " 100%";
@@ -330,9 +330,9 @@ function updateGeneralPanelCounter(allCounters)
 
 				if (g_Teams[t])
 				{
-					let yStart = 25 + g_Teams[t].length * (g_PlayerBoxYSize + g_PlayerBoxGap) + 3;
+					const yStart = 25 + g_Teams[t].length * (g_PlayerBoxYSize + g_PlayerBoxGap) + 3;
 					counterTotalObject = Engine.GetGUIObjectByName("valueDataTeam[" + t + "][" + w + "]");
-					let yStartTotal = 14 + g_Teams[t].length * (g_PlayerBoxYSize + g_PlayerBoxGap) + 10;
+					const yStartTotal = 14 + g_Teams[t].length * (g_PlayerBoxYSize + g_PlayerBoxGap) + 10;
 					counterTotalObject.size = (left + 20) + " " + yStartTotal + " " + (left + counters[w].width) + " " + (yStartTotal + 52);
 					counterTotalObject.hidden = false;
 				}
@@ -346,7 +346,7 @@ function updateGeneralPanelCounter(allCounters)
 
 function updateGeneralPanelTeams()
 {
-	let withoutTeam = !g_Teams[-1] ? 0 : g_Teams[-1].length;
+	const withoutTeam = !g_Teams[-1] ? 0 : g_Teams[-1].length;
 
 	if (!g_Teams || withoutTeam > 0)
 		Engine.GetGUIObjectByName("noTeamsBox").hidden = false;
@@ -355,14 +355,14 @@ function updateGeneralPanelTeams()
 		return;
 
 	let yStart = g_TeamsBoxYStart + withoutTeam * (g_PlayerBoxYSize + g_PlayerBoxGap) + (withoutTeam ? 30 : 0);
-	for (let i in g_Teams)
+	for (const i in g_Teams)
 	{
 		if (i == -1)
 			continue;
 
-		let teamBox = Engine.GetGUIObjectByName("teamBoxt["+i+"]");
+		const teamBox = Engine.GetGUIObjectByName("teamBoxt["+i+"]");
 		teamBox.hidden = false;
-		let teamBoxSize = teamBox.size;
+		const teamBoxSize = teamBox.size;
 		teamBoxSize.top = yStart;
 		teamBox.size = teamBoxSize;
 
@@ -370,8 +370,8 @@ function updateGeneralPanelTeams()
 
 		Engine.GetGUIObjectByName("teamNameHeadingt[" + i + "]").caption = "Team " + (+i + 1);
 
-		let teamHeading = Engine.GetGUIObjectByName("teamHeadingt[" + i + "]");
-		let yStartTotal = 14 + g_Teams[i].length * (g_PlayerBoxYSize + g_PlayerBoxGap) + 10;
+		const teamHeading = Engine.GetGUIObjectByName("teamHeadingt[" + i + "]");
+		const yStartTotal = 14 + g_Teams[i].length * (g_PlayerBoxYSize + g_PlayerBoxGap) + 10;
 		teamHeading.size = "50 " + yStartTotal + " 100% " + (yStartTotal + 52);
 		teamHeading.caption = translate("Team total");
 	}
@@ -385,7 +385,7 @@ function initPlayerBoxPositions()
 {
 	for (let h = 0; h < g_MaxPlayers; ++h)
 	{
-		let playerBox = Engine.GetGUIObjectByName("playerBox[" + h + "]");
+		const playerBox = Engine.GetGUIObjectByName("playerBox[" + h + "]");
 		let boxSize = playerBox.size;
 		boxSize.top += h * (g_PlayerBoxYSize + g_PlayerBoxGap);
 		boxSize.bottom = boxSize.top + g_PlayerBoxYSize;
@@ -393,7 +393,7 @@ function initPlayerBoxPositions()
 
 		for (let i = 0; i < g_MaxTeams; ++i)
 		{
-			let playerBoxt = Engine.GetGUIObjectByName("playerBoxt[" + i + "][" + h + "]");
+			const playerBoxt = Engine.GetGUIObjectByName("playerBoxt[" + i + "][" + h + "]");
 			boxSize = playerBoxt.size;
 			boxSize.top += h * (g_PlayerBoxYSize + g_PlayerBoxGap);
 			boxSize.bottom = boxSize.top + g_PlayerBoxYSize;
diff --git a/binaries/data/mods/public/gui/summary/summary.js b/binaries/data/mods/public/gui/summary/summary.js
index d57a1eb54b..d7555b5bf4 100644
--- a/binaries/data/mods/public/gui/summary/summary.js
+++ b/binaries/data/mods/public/gui/summary/summary.js
@@ -185,7 +185,7 @@ function initGUISummary()
  */
 function initGUIWindow()
 {
-	let summaryWindow = Engine.GetGUIObjectByName("summaryWindow");
+	const summaryWindow = Engine.GetGUIObjectByName("summaryWindow");
 	summaryWindow.sprite = g_GameData.gui.dialog ? "ModernDialog" : "ModernWindow";
 	summaryWindow.size = g_GameData.gui.dialog ? "16 24 100%-16 100%-24" : "0 0 100% 100%";
 	Engine.GetGUIObjectByName("summaryWindowTitle").size = g_GameData.gui.dialog ? "50%-128 -16 50%+128 16" : "50%-128 4 50%+128 36";
@@ -195,11 +195,11 @@ function selectPanelGUI(panel)
 {
 	adjustTabDividers(Engine.GetGUIObjectByName("tabButton[" + panel + "]").size);
 
-	let generalPanel = Engine.GetGUIObjectByName("generalPanel");
-	let chartsPanel = Engine.GetGUIObjectByName("chartsPanel");
+	const generalPanel = Engine.GetGUIObjectByName("generalPanel");
+	const chartsPanel = Engine.GetGUIObjectByName("chartsPanel");
 
 	// We assume all scorePanels come before the charts.
-	let chartsHidden = panel < g_ScorePanelsData.length;
+	const chartsHidden = panel < g_ScorePanelsData.length;
 	generalPanel.hidden = !chartsHidden;
 	chartsPanel.hidden = chartsHidden;
 	if (chartsHidden)
@@ -221,10 +221,10 @@ function constructPlayersWithColor(color, playerListing)
 
 function updateChartColorAndLegend()
 {
-	let playerColors = [];
+	const playerColors = [];
 	for (let i = 1; i <= g_PlayerCount; ++i)
 	{
-		let playerState = g_GameData.sim.playerStates[i];
+		const playerState = g_GameData.sim.playerStates[i];
 		playerColors.push(
 			Math.floor(playerState.color.r * 255) + " " +
 			Math.floor(playerState.color.g * 255) + " " +
@@ -238,7 +238,7 @@ function updateChartColorAndLegend()
 				g_Teams.filter(el => el !== null).map(players => playerColors[players[0] - 1]) :
 				playerColors;
 
-	let chartLegend = Engine.GetGUIObjectByName("chartLegend");
+	const chartLegend = Engine.GetGUIObjectByName("chartLegend");
 	chartLegend.caption = (Engine.GetGUIObjectByName("toggleTeamBox").checked ?
 		g_Teams.filter(el => el !== null).map(players =>
 			constructPlayersWithColor(playerColors[players[0] - 1],	players.map(player =>
@@ -253,8 +253,8 @@ function updateChartColorAndLegend()
 function initGUICharts()
 {
 	updateChartColorAndLegend();
-	let chart1Part = Engine.GetGUIObjectByName("chart[1]Part");
-	let chart1PartSize = chart1Part.size;
+	const chart1Part = Engine.GetGUIObjectByName("chart[1]Part");
+	const chart1PartSize = chart1Part.size;
 	chart1PartSize.rright += 50;
 	chart1PartSize.rleft += 50;
 	chart1PartSize.right -= 5;
@@ -265,7 +265,7 @@ function initGUICharts()
 
 function resizeDropdown(dropdown)
 {
-	let size = dropdown.size;
+	const size = dropdown.size;
 	size.bottom = dropdown.size.top +
 		(Engine.GetTextWidth(dropdown.font, dropdown.list[dropdown.selected]) >
 			dropdown.size.right - dropdown.size.left - 28 &&
@@ -275,7 +275,7 @@ function resizeDropdown(dropdown)
 
 function updateCategoryDropdown(number)
 {
-	let chartCategory = Engine.GetGUIObjectByName("chart[" + number + "]CategorySelection");
+	const chartCategory = Engine.GetGUIObjectByName("chart[" + number + "]CategorySelection");
 	chartCategory.list_data = g_ScorePanelsData.map((panel, idx) => idx);
 	chartCategory.list = g_ScorePanelsData.map(panel => panel.label);
 	chartCategory.onSelectionChange = function() {
@@ -296,11 +296,11 @@ function updateCategoryDropdown(number)
 
 function updateValueDropdown(number, category)
 {
-	let chartValue = Engine.GetGUIObjectByName("chart[" + number + "]ValueSelection");
-	let list = g_ScorePanelsData[category].headings.map(heading => heading.caption);
+	const chartValue = Engine.GetGUIObjectByName("chart[" + number + "]ValueSelection");
+	const list = g_ScorePanelsData[category].headings.map(heading => heading.caption);
 	list.shift();
 	chartValue.list = list;
-	let list_data = g_ScorePanelsData[category].headings.map(heading => heading.identifier);
+	const list_data = g_ScorePanelsData[category].headings.map(heading => heading.identifier);
 	list_data.shift();
 	chartValue.list_data = list_data;
 	chartValue.onSelectionChange = function() {
@@ -320,11 +320,11 @@ function updateValueDropdown(number, category)
 
 function updateTypeDropdown(number, category, item, itemNumber)
 {
-	let testValue = g_ScorePanelsData[category].counters[itemNumber].fn(g_GameData.sim.playerStates[1], 0, item);
-	let hide = !g_ScorePanelsData[category].counters[itemNumber].fn ||
+	const testValue = g_ScorePanelsData[category].counters[itemNumber].fn(g_GameData.sim.playerStates[1], 0, item);
+	const hide = !g_ScorePanelsData[category].counters[itemNumber].fn ||
 		typeof testValue != "object" || Object.keys(testValue).length < 2;
 	Engine.GetGUIObjectByName("chart[" + number + "]TypeLabel").hidden = hide;
-	let chartType = Engine.GetGUIObjectByName("chart[" + number + "]TypeSelection");
+	const chartType = Engine.GetGUIObjectByName("chart[" + number + "]TypeSelection");
 	chartType.hidden = hide;
 	if (hide)
 	{
@@ -348,16 +348,16 @@ function updateChart(number, category, item, itemNumber, type)
 {
 	if (!g_ScorePanelsData[category].counters[itemNumber].fn)
 		return;
-	let chart = Engine.GetGUIObjectByName("chart[" + number + "]");
+	const chart = Engine.GetGUIObjectByName("chart[" + number + "]");
 	chart.format_y = g_ScorePanelsData[category].headings[itemNumber + 1].format || "INTEGER";
 	Engine.GetGUIObjectByName("chart[" + number + "]XAxisLabel").caption = translate("Time elapsed");
 
-	let series = [];
+	const series = [];
 	if (Engine.GetGUIObjectByName("toggleTeamBox").checked)
-		for (let team in g_Teams)
+		for (const team in g_Teams)
 		{
-			let data = [];
-			for (let index in g_GameData.sim.playerStates[1].sequences.time)
+			const data = [];
+			for (const index in g_GameData.sim.playerStates[1].sequences.time)
 			{
 				let value = g_ScorePanelsData[category].teamCounterFn(team, index, item,
 					g_ScorePanelsData[category].counters, g_ScorePanelsData[category].headings);
@@ -370,9 +370,9 @@ function updateChart(number, category, item, itemNumber, type)
 	else
 		for (let j = 1; j <= g_PlayerCount; ++j)
 		{
-			let playerState = g_GameData.sim.playerStates[j];
-			let data = [];
-			for (let index in playerState.sequences.time)
+			const playerState = g_GameData.sim.playerStates[j];
+			const data = [];
+			for (const index in playerState.sequences.time)
 			{
 				let value = g_ScorePanelsData[category].counters[itemNumber].fn(playerState, index, item);
 				if (type)
@@ -387,15 +387,15 @@ function updateChart(number, category, item, itemNumber, type)
 
 function adjustTabDividers(tabSize)
 {
-	let tabButtonsLeft = Engine.GetGUIObjectByName("tabButtonsFrame").size.left;
+	const tabButtonsLeft = Engine.GetGUIObjectByName("tabButtonsFrame").size.left;
 
-	let leftSpacer = Engine.GetGUIObjectByName("tabDividerLeft");
-	let leftSpacerSize = leftSpacer.size;
+	const leftSpacer = Engine.GetGUIObjectByName("tabDividerLeft");
+	const leftSpacerSize = leftSpacer.size;
 	leftSpacerSize.right = tabSize.left + tabButtonsLeft + 2;
 	leftSpacer.size = leftSpacerSize;
 
-	let rightSpacer = Engine.GetGUIObjectByName("tabDividerRight");
-	let rightSpacerSize = rightSpacer.size;
+	const rightSpacer = Engine.GetGUIObjectByName("tabDividerRight");
+	const rightSpacerSize = rightSpacer.size;
 	rightSpacerSize.left = tabSize.right + tabButtonsLeft - 2;
 	rightSpacer.size = rightSpacerSize;
 }
@@ -405,21 +405,21 @@ function updatePanelData(panelInfo)
 	resetGeneralPanel();
 	updateGeneralPanelHeadings(panelInfo.headings);
 	updateGeneralPanelTitles(panelInfo.titleHeadings);
-	let rowPlayerObjectWidth = updateGeneralPanelCounter(panelInfo.counters);
+	const rowPlayerObjectWidth = updateGeneralPanelCounter(panelInfo.counters);
 	updateGeneralPanelTeams();
 
-	let index = g_GameData.sim.playerStates[1].sequences.time.length - 1;
-	let playerBoxesCounts = [];
+	const index = g_GameData.sim.playerStates[1].sequences.time.length - 1;
+	const playerBoxesCounts = [];
 	for (let i = 0; i < g_PlayerCount; ++i)
 	{
-		let playerState = g_GameData.sim.playerStates[i + 1];
+		const playerState = g_GameData.sim.playerStates[i + 1];
 
 		if (!playerBoxesCounts[playerState.team + 1])
 			playerBoxesCounts[playerState.team + 1] = 1;
 		else
 			playerBoxesCounts[playerState.team + 1] += 1;
 
-		let positionObject = playerBoxesCounts[playerState.team + 1] - 1;
+		const positionObject = playerBoxesCounts[playerState.team + 1] - 1;
 		let rowPlayer = "playerBox[" + positionObject + "]";
 		let playerOutcome = "playerOutcome[" + positionObject + "]";
 		let playerNameColumn = "playerName[" + positionObject + "]";
@@ -435,16 +435,16 @@ function updatePanelData(panelInfo)
 			playerCounterValue = "valueDataTeam[" + playerState.team + "][" + positionObject + "]";
 		}
 
-		let colorString = "color: " +
+		const colorString = "color: " +
 			Math.floor(playerState.color.r * 255) + " " +
 			Math.floor(playerState.color.g * 255) + " " +
 			Math.floor(playerState.color.b * 255);
 
-		let rowPlayerObject = Engine.GetGUIObjectByName(rowPlayer);
+		const rowPlayerObject = Engine.GetGUIObjectByName(rowPlayer);
 		rowPlayerObject.hidden = false;
 		rowPlayerObject.sprite = colorString + " " + g_PlayerBoxAlpha;
 
-		let boxSize = rowPlayerObject.size;
+		const boxSize = rowPlayerObject.size;
 		boxSize.right = rowPlayerObjectWidth;
 		rowPlayerObject.size = boxSize;
 
@@ -454,21 +454,21 @@ function updatePanelData(panelInfo)
 		playerNameColumn.caption = g_GameData.sim.playerStates[i + 1].name;
 		playerNameColumn.tooltip = translateAISettings(g_GameData.sim.mapSettings.PlayerData[i + 1]);
 
-		let civIcon = Engine.GetGUIObjectByName(playerCivicBoxColumn);
+		const civIcon = Engine.GetGUIObjectByName(playerCivicBoxColumn);
 		civIcon.sprite = "stretched:" + g_CivData[playerState.civ].Emblem;
 		civIcon.tooltip = g_CivData[playerState.civ].Name;
 
 		updateCountersPlayer(playerState, panelInfo.counters, panelInfo.headings, playerCounterValue, index);
 	}
 
-	let teamCounterFn = panelInfo.teamCounterFn;
+	const teamCounterFn = panelInfo.teamCounterFn;
 	if (g_Teams && teamCounterFn)
 		updateCountersTeam(teamCounterFn, panelInfo.counters, panelInfo.headings, index);
 }
 
 function continueButton(gameData)
 {
-	let summarySelection = {
+	const summarySelection = {
 		"panel": g_TabCategorySelected,
 		"charts": g_SelectedChart,
 		"teamCharts": Engine.GetGUIObjectByName("toggleTeamBox").checked
@@ -518,7 +518,7 @@ function startReplay()
 
 function initGUILabels()
 {
-	let assignedState = g_GameData.sim.playerStates[g_GameData.gui.assignedPlayer || -1];
+	const assignedState = g_GameData.sim.playerStates[g_GameData.gui.assignedPlayer || -1];
 
 	Engine.GetGUIObjectByName("summaryText").caption =
 		g_GameData.gui.isInGame ?
@@ -540,8 +540,8 @@ function initGUILabels()
 			"time": timeToString(g_GameData.sim.timeElapsed)
 		});
 
-	let mapType = g_Settings.MapTypes.find(type => type.Name == g_GameData.sim.mapSettings.mapType);
-	let mapSize = g_Settings.MapSizes.find(size => size.Tiles == g_GameData.sim.mapSettings.Size || 0);
+	const mapType = g_Settings.MapTypes.find(type => type.Name == g_GameData.sim.mapSettings.mapType);
+	const mapSize = g_Settings.MapSizes.find(size => size.Tiles == g_GameData.sim.mapSettings.Size || 0);
 
 	Engine.GetGUIObjectByName("mapName").caption = sprintf(
 		translate("%(mapName)s - %(mapType)s"), {
@@ -552,22 +552,22 @@ function initGUILabels()
 
 function initGUIButtons()
 {
-	let replayButton = Engine.GetGUIObjectByName("replayButton");
+	const replayButton = Engine.GetGUIObjectByName("replayButton");
 	replayButton.hidden = g_GameData.gui.isInGame || !g_GameData.gui.replayDirectory;
 
-	let lobbyButton = Engine.GetGUIObjectByName("lobbyButton");
+	const lobbyButton = Engine.GetGUIObjectByName("lobbyButton");
 	lobbyButton.tooltip = colorizeHotkey(translate("%(hotkey)s: Toggle the multiplayer lobby in a dialog window."), "lobby");
 	lobbyButton.hidden = g_GameData.gui.isInGame || !Engine.HasXmppClient();
 
 	// Right-align lobby button
-	let lobbyButtonSize = lobbyButton.size;
-	let lobbyButtonWidth = lobbyButtonSize.right - lobbyButtonSize.left;
+	const lobbyButtonSize = lobbyButton.size;
+	const lobbyButtonWidth = lobbyButtonSize.right - lobbyButtonSize.left;
 	lobbyButtonSize.right = (replayButton.hidden ? Engine.GetGUIObjectByName("continueButton").size.left : replayButton.size.left) - 10;
 	lobbyButtonSize.left = lobbyButtonSize.right - lobbyButtonWidth;
 	lobbyButton.size = lobbyButtonSize;
 
-	let allPanelsData = g_ScorePanelsData.concat(g_ChartPanelsData);
-	for (let tab in allPanelsData)
+	const allPanelsData = g_ScorePanelsData.concat(g_ChartPanelsData);
+	for (const tab in allPanelsData)
 		allPanelsData[tab].tooltip = sprintf(translate("Focus the %(name)s summary tab."), { "name": allPanelsData[tab].label });
 
 	placeTabButtons(
@@ -589,7 +589,7 @@ function initTeamData()
 		// Count teams
 		for (let player = 1; player <= g_PlayerCount; ++player)
 		{
-			let playerTeam = g_GameData.sim.playerStates[player].team;
+			const playerTeam = g_GameData.sim.playerStates[player].team;
 			if (!g_Teams[playerTeam])
 				g_Teams[playerTeam] = [];
 			g_Teams[playerTeam].push(player);
diff --git a/binaries/data/mods/public/maps/skirmishes/gallic_fields_3p.js b/binaries/data/mods/public/maps/skirmishes/gallic_fields_3p.js
index f1973d4dc9..9259351b26 100644
--- a/binaries/data/mods/public/maps/skirmishes/gallic_fields_3p.js
+++ b/binaries/data/mods/public/maps/skirmishes/gallic_fields_3p.js
@@ -36,7 +36,7 @@ Trigger.prototype.SpawnAndAttack = function()
 };
 
 {
-	let cmpTrigger = Engine.QueryInterface(SYSTEM_ENTITY, IID_Trigger);
+	const cmpTrigger = Engine.QueryInterface(SYSTEM_ENTITY, IID_Trigger);
 	cmpTrigger.attackSize = 1; // attack with 1 soldier
 	cmpTrigger.attackTime = 60 * 1000; // attack in 1 minute
 	cmpTrigger.DoAfterDelay(cmpTrigger.attackTime, "SpawnAndAttack", {});
diff --git a/binaries/data/mods/public/maps/tutorials/introductory_tutorial.js b/binaries/data/mods/public/maps/tutorials/introductory_tutorial.js
index e6d62d4847..621f2bc85f 100644
--- a/binaries/data/mods/public/maps/tutorials/introductory_tutorial.js
+++ b/binaries/data/mods/public/maps/tutorials/introductory_tutorial.js
@@ -31,9 +31,9 @@ Trigger.prototype.tutorialGoals = [
 		{
 			if (msg.unitTemplate != "units/spart/infantry_spearman_b" || +msg.count == 1)
 			{
-				let cmpProductionQueue = Engine.QueryInterface(msg.trainerEntity, IID_ProductionQueue);
+				const cmpProductionQueue = Engine.QueryInterface(msg.trainerEntity, IID_ProductionQueue);
 				cmpProductionQueue.ResetQueue();
-				let txt = +msg.count == 1 ?
+				const txt = +msg.count == 1 ?
 					markForTranslation("Do not forget to press the batch training hotkey while clicking to produce multiple units.") :
 					markForTranslation("Click on the Hoplite icon.");
 				this.WarningMessage(txt);
@@ -73,9 +73,9 @@ Trigger.prototype.tutorialGoals = [
 		{
 			if (msg.unitTemplate != "units/spart/infantry_javelineer_b" || +msg.count == 1)
 			{
-				let cmpProductionQueue = Engine.QueryInterface(msg.trainerEntity, IID_ProductionQueue);
+				const cmpProductionQueue = Engine.QueryInterface(msg.trainerEntity, IID_ProductionQueue);
 				cmpProductionQueue.ResetQueue();
-				let txt = +msg.count == 1 ?
+				const txt = +msg.count == 1 ?
 					markForTranslation("Do not forget to press the batch training hotkey while clicking to produce multiple units.") :
 					markForTranslation("Click on the Skirmisher icon.");
 				this.WarningMessage(txt);
@@ -155,9 +155,9 @@ Trigger.prototype.tutorialGoals = [
 		{
 			if (msg.unitTemplate != "units/spart/infantry_spearman_b" || +msg.count == 1)
 			{
-				let cmpProductionQueue = Engine.QueryInterface(msg.trainerEntity, IID_ProductionQueue);
+				const cmpProductionQueue = Engine.QueryInterface(msg.trainerEntity, IID_ProductionQueue);
 				cmpProductionQueue.ResetQueue();
-				let txt = +msg.count == 1 ?
+				const txt = +msg.count == 1 ?
 					markForTranslation("Do not forget to press the batch training hotkey while clicking to produce multiple units.") :
 					markForTranslation("Click on the Hoplite icon.");
 				this.WarningMessage(txt);
@@ -205,9 +205,9 @@ Trigger.prototype.tutorialGoals = [
 		"instructions": markForTranslation("While waiting for the phasing up, you may reassign your idle workers to gathering the resources you are short of."),
 		"IsDone": function()
 		{
-			let cmpPlayerManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_PlayerManager);
-			let playerEnt = cmpPlayerManager.GetPlayerByID(this.playerID);
-			let cmpTechnologyManager = Engine.QueryInterface(playerEnt, IID_TechnologyManager);
+			const cmpPlayerManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_PlayerManager);
+			const playerEnt = cmpPlayerManager.GetPlayerByID(this.playerID);
+			const cmpTechnologyManager = Engine.QueryInterface(playerEnt, IID_TechnologyManager);
 			return cmpTechnologyManager && cmpTechnologyManager.IsTechnologyResearched("phase_town_generic");
 		},
 		"OnResearchFinished": function(msg)
@@ -239,9 +239,9 @@ Trigger.prototype.tutorialGoals = [
 		{
 			if (msg.unitTemplate != "units/spart/support_female_citizen" || +msg.count == 1)
 			{
-				let cmpProductionQueue = Engine.QueryInterface(msg.trainerEntity, IID_ProductionQueue);
+				const cmpProductionQueue = Engine.QueryInterface(msg.trainerEntity, IID_ProductionQueue);
 				cmpProductionQueue.ResetQueue();
-				let txt = +msg.count == 1 ?
+				const txt = +msg.count == 1 ?
 					markForTranslation("Do not forget to press the batch training hotkey while clicking to produce multiple units.") :
 					markForTranslation("Click on the Female Citizen icon.");
 				this.WarningMessage(txt);
@@ -379,7 +379,7 @@ Trigger.prototype.tutorialGoals = [
 		"instructions": markForTranslation("The enemy has been defeated. These tutorial tasks are now completed."),
 		"Init": function()
 		{
-			let cmpEndGameManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_EndGameManager);
+			const cmpEndGameManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_EndGameManager);
 			cmpEndGameManager.MarkPlayerAndAlliesAsWon(1, () => "Tutorial completed", () => "");
 		}
 	}
@@ -387,22 +387,22 @@ Trigger.prototype.tutorialGoals = [
 
 Trigger.prototype.LaunchAttack = function()
 {
-	let cmpRangeManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_RangeManager);
-	let entities = cmpRangeManager.GetEntitiesByPlayer(this.playerID);
-	let target =
+	const cmpRangeManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_RangeManager);
+	const entities = cmpRangeManager.GetEntitiesByPlayer(this.playerID);
+	const target =
 		entities.find(e => {
-			let cmpIdentity = Engine.QueryInterface(e, IID_Identity);
+			const cmpIdentity = Engine.QueryInterface(e, IID_Identity);
 			return cmpIdentity && cmpIdentity.HasClass("Tower") && Engine.QueryInterface(e, IID_Position);
 		}) ||
 		entities.find(e => {
-			let cmpIdentity = Engine.QueryInterface(e, IID_Identity);
+			const cmpIdentity = Engine.QueryInterface(e, IID_Identity);
 			return cmpIdentity && cmpIdentity.HasClass("CivilCentre") && Engine.QueryInterface(e, IID_Position);
 		});
 
-	let position = Engine.QueryInterface(target, IID_Position).GetPosition2D();
+	const position = Engine.QueryInterface(target, IID_Position).GetPosition2D();
 
 	this.attackers = cmpRangeManager.GetEntitiesByPlayer(this.enemyID).filter(e => {
-		let cmpIdentity = Engine.QueryInterface(e, IID_Identity);
+		const cmpIdentity = Engine.QueryInterface(e, IID_Identity);
 		return Engine.QueryInterface(e, IID_UnitAI) && cmpIdentity && cmpIdentity.HasClass("CitizenSoldier");
 	});
 
@@ -424,12 +424,12 @@ Trigger.prototype.IsAttackRepelled = function()
 
 Trigger.prototype.RemoveChampions = function()
 {
-	let cmpRangeManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_RangeManager);
-	let champions = cmpRangeManager.GetEntitiesByPlayer(this.enemyID).filter(e => Engine.QueryInterface(e, IID_Identity).HasClass("Champion"));
+	const cmpRangeManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_RangeManager);
+	const champions = cmpRangeManager.GetEntitiesByPlayer(this.enemyID).filter(e => Engine.QueryInterface(e, IID_Identity).HasClass("Champion"));
 	let keep = 6;
-	for (let ent of champions)
+	for (const ent of champions)
 	{
-		let cmpHealth = Engine.QueryInterface(ent, IID_Health);
+		const cmpHealth = Engine.QueryInterface(ent, IID_Health);
 		if (!cmpHealth)
 			Engine.DestroyEntity(ent);
 		else if (--keep < 0)
@@ -438,7 +438,7 @@ Trigger.prototype.RemoveChampions = function()
 };
 
 {
-	let cmpTrigger = Engine.QueryInterface(SYSTEM_ENTITY, IID_Trigger);
+	const cmpTrigger = Engine.QueryInterface(SYSTEM_ENTITY, IID_Trigger);
 	cmpTrigger.playerID = 1;
 	cmpTrigger.enemyID = 2;
 	cmpTrigger.RegisterTrigger("OnInitGame", "InitTutorial", { "enabled": true });
diff --git a/binaries/data/mods/public/maps/tutorials/starting_economy_walkthrough.js b/binaries/data/mods/public/maps/tutorials/starting_economy_walkthrough.js
index 6d640a9a62..eb8dde02a0 100644
--- a/binaries/data/mods/public/maps/tutorials/starting_economy_walkthrough.js
+++ b/binaries/data/mods/public/maps/tutorials/starting_economy_walkthrough.js
@@ -104,10 +104,10 @@ Trigger.prototype.tutorialGoals = [
 		{
 			if (msg.unitTemplate != "units/athen/infantry_spearman_b" || +msg.count == 1)
 			{
-				let entity = msg.trainerEntity;
-				let cmpProductionQueue = Engine.QueryInterface(entity, IID_ProductionQueue);
+				const entity = msg.trainerEntity;
+				const cmpProductionQueue = Engine.QueryInterface(entity, IID_ProductionQueue);
 				cmpProductionQueue.ResetQueue();
-				let txt = +msg.count == 1 ?
+				const txt = +msg.count == 1 ?
 					markForTranslation("Do not forget to hold Shift while clicking to train several units.") :
 					markForTranslation("Hold Shift and click on the Hoplite icon.");
 				this.WarningMessage(txt);
@@ -145,7 +145,7 @@ Trigger.prototype.tutorialGoals = [
 		],
 		"OnStructureBuilt": function(msg)
 		{
-			let cmpResourceDropsite = Engine.QueryInterface(msg.building, IID_ResourceDropsite);
+			const cmpResourceDropsite = Engine.QueryInterface(msg.building, IID_ResourceDropsite);
 			if (cmpResourceDropsite && cmpResourceDropsite.AcceptsType("wood"))
 				this.NextGoal();
 		},
@@ -163,10 +163,10 @@ Trigger.prototype.tutorialGoals = [
 		{
 			if (msg.unitTemplate != "units/athen/support_female_citizen" || +msg.count == 1)
 			{
-				let entity = msg.trainerEntity;
-				let cmpProductionQueue = Engine.QueryInterface(entity, IID_ProductionQueue);
+				const entity = msg.trainerEntity;
+				const cmpProductionQueue = Engine.QueryInterface(entity, IID_ProductionQueue);
 				cmpProductionQueue.ResetQueue();
-				let txt = +msg.count == 1 ?
+				const txt = +msg.count == 1 ?
 					markForTranslation("Do not forget to hold Shift and click to train several units.") :
 					markForTranslation("Hold shift and click on the Female Citizen icon.");
 				this.WarningMessage(txt);
@@ -229,7 +229,7 @@ Trigger.prototype.tutorialGoals = [
 			if (msg.from != INVALID_PLAYER && this.houseGoal.has(+msg.entity))
 			{
 				this.houseGoal.delete(+msg.entity);
-				let cmpFoundation = Engine.QueryInterface(+msg.entity, IID_Foundation);
+				const cmpFoundation = Engine.QueryInterface(+msg.entity, IID_Foundation);
 				if (cmpFoundation && cmpFoundation.GetBuildProgress() < 1)	// Destroyed before built
 					--this.houseCount;
 			}
@@ -340,10 +340,10 @@ Trigger.prototype.tutorialGoals = [
 		{
 			if (msg.unitTemplate != "units/athen/support_female_citizen" || +msg.count != 1)
 			{
-				let entity = msg.trainerEntity;
-				let cmpProductionQueue = Engine.QueryInterface(entity, IID_ProductionQueue);
+				const entity = msg.trainerEntity;
+				const cmpProductionQueue = Engine.QueryInterface(entity, IID_ProductionQueue);
 				cmpProductionQueue.ResetQueue();
-				let txt = +msg.count != 1 ?
+				const txt = +msg.count != 1 ?
 					markForTranslation("Click without holding Shift to train a single unit.") :
 					markForTranslation("Click on the Female Citizen icon.");
 				this.WarningMessage(txt);
@@ -456,7 +456,7 @@ Trigger.prototype.tutorialGoals = [
 ];
 
 {
-	let cmpTrigger = Engine.QueryInterface(SYSTEM_ENTITY, IID_Trigger);
+	const cmpTrigger = Engine.QueryInterface(SYSTEM_ENTITY, IID_Trigger);
 	cmpTrigger.playerID = 1;
 	cmpTrigger.RegisterTrigger("OnInitGame", "InitTutorial", { "enabled": true });
 }
diff --git a/source/tools/rlclient/python/tests/fastactions.js b/source/tools/rlclient/python/tests/fastactions.js
index 20a0a67c94..855c5bbae4 100644
--- a/source/tools/rlclient/python/tests/fastactions.js
+++ b/source/tools/rlclient/python/tests/fastactions.js
@@ -1,6 +1,6 @@
-let cmpPlayerManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_PlayerManager);
-let playerEnt = cmpPlayerManager.GetPlayerByID('1');
-let cmpModifiersManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_ModifiersManager);
+const cmpPlayerManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_PlayerManager);
+const playerEnt = cmpPlayerManager.GetPlayerByID('1');
+const cmpModifiersManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_ModifiersManager);
 cmpModifiersManager.AddModifiers("cheat/fastactions", {
 	"Cost/BuildTime": [{ "affects": [["Structure"], ["Unit"]], "multiply": 0.01 }],
 	"ResourceGatherer/BaseSpeed": [{ "affects": [["Structure"], ["Unit"]], "multiply": 1000 }],