diff --git a/main.js b/main.js
index f0ba76b3..514c0939 100644
--- a/main.js
+++ b/main.js
@@ -323,10 +323,12 @@ function applyDefaultBiomesSystem() {
   ];
 
   // parse icons weighted array into a simple array
-  for (let i=0; i < icons.length; i++) {
+  var iconsNum = icons.length;
+  for (let i=0; i < iconsNum; i++) {
     const parsed = [];
     for (const icon in icons[i]) {
-      for (let j = 0; j < icons[i][icon]; j++) {parsed.push(icon);}
+      var iconVal = icons[i][icon];
+      for (let j = 0; j < iconVal; j++) {parsed.push(icon);}
     }
     icons[i] = parsed;
   }
@@ -763,7 +765,8 @@ function calculateTemperatures() {
     const y = grid.points[r][1];
     const lat = Math.abs(mapCoordinates.latN - y / graphHeight * mapCoordinates.latT); // [0; 90]
     const initTemp = tEq - int(lat / 90) * tDelta;
-    for (let i = r; i < r+grid.cellsX; i++) {
+    let rPlusCellsX = r+grid.cellsX;
+    for (let i = r; i < rPlusCellsX; i++) {
       cells.temp[i] = Math.max(Math.min(initTemp - convertToFriendly(cells.h[i]), 127), -128);
     }
   });
@@ -1030,8 +1033,8 @@ function drawCoastline() {
   // move vertices that are too close to already added ones
   function relax(vchain, r) {
     const p = vertices.p, tree = d3.quadtree();
-
-    for (let i=0; i < vchain.length; i++) {
+    var vchainLength = vchain.length;
+    for (let i=0; i < vchainLength; i++) {
       const v = vchain[i];
       let [x, y] = [p[v][0], p[v][1]];
       if (i && vchain[i+1] && tree.find(x, y, r) !== undefined) {
@@ -1302,7 +1305,8 @@ function addMarkers(number = 1) {
     const animal = ["Antelope", "Ape", "Badger", "Bear", "Beaver", "Bison", "Boar", "Buffalo", "Cat", "Crane", "Crocodile", "Crow", "Deer", "Dog", "Eagle", "Elk", "Fox", "Goat", "Goose", "Hare", "Hawk", "Heron", "Horse", "Hyena", "Ibis", "Jackal", "Jaguar", "Lark", "Leopard", "Lion", "Mantis", "Marten", "Moose", "Mule", "Narwhal", "Owl", "Panther", "Rat", "Raven", "Rook", "Scorpion", "Shark", "Sheep", "Snake", "Spider", "Swan", "Tiger", "Turtle", "Wolf", "Wolverine", "Camel", "Falcon", "Hound", "Ox"];
     const adj = ["New", "Good", "High", "Old", "Great", "Big", "Major", "Happy", "Main", "Huge", "Far", "Beautiful", "Fair", "Prime", "Ancient", "Golden", "Proud", "Lucky", "Fat", "Honest", "Giant", "Distant", "Friendly", "Loud", "Hungry", "Magical", "Superior", "Peaceful", "Frozen", "Divine", "Favorable", "Brave", "Sunny", "Flying"];
 
-    for (let i=0; i < taverns.length && i < count; i++) {
+    let numberOfTaverns = taverns.length;
+    for (let i=0; i < numberOfTaverns && i < count; i++) {
       const cell = taverns.splice(Math.floor(Math.random() * taverns.length), 1);
       const id = appendMarker(cell, "inn");
       const type = P(.3) ? "inn" : "tavern";
@@ -1317,7 +1321,8 @@ function addMarkers(number = 1) {
     if (lighthouses.length) addMarker("lighthouse", "🚨", 50, 50, 16);
     const count = Math.ceil(4 * number);
 
-    for (let i=0; i < lighthouses.length && i < count; i++) {
+    let numberOfLighthouses = lighthouses.length;
+    for (let i=0; i < numberOfLighthouses && i < count; i++) {
       const cell = lighthouses[i][0], vertex = lighthouses[i][1];
       const id = appendMarker(cell, "lighthouse");
       const proper = cells.burg[cell] ? pack.burgs[cells.burg[cell]].name : Names.getCulture(cells.culture[cell]);
@@ -1330,7 +1335,8 @@ function addMarkers(number = 1) {
     if (waterfalls.length) addMarker("waterfall", "⟱", 50, 54, 16.5);
     const count = Math.ceil(3 * number);
 
-    for (let i=0; i < waterfalls.length && i < count; i++) {
+    let numberOfWaterfalls = waterfalls.length;
+    for (let i=0; i < numberOfWaterfalls && i < count; i++) {
       const cell = waterfalls[i];
       const id = appendMarker(cell, "waterfall");
       const proper = cells.burg[cell] ? pack.burgs[cells.burg[cell]].name : Names.getCulture(cells.culture[cell]);
diff --git a/modules/burgs-and-states.js b/modules/burgs-and-states.js
index abe8e1c7..a0420c58 100644
--- a/modules/burgs-and-states.js
+++ b/modules/burgs-and-states.js
@@ -112,7 +112,8 @@
       let spacing = (graphWidth + graphHeight) / 150 / (burgsNumber ** .7 / 66); // min distance between towns
 
       while (burgsAdded < burgsNumber && spacing > 1) {
-        for (let i=0; burgsAdded < burgsNumber && i < sorted.length; i++) {
+        let sortedArrayLength = sorted.length;
+        for (let i=0; burgsAdded < burgsNumber && i < sortedArrayLength; i++) {
           if (cells.burg[sorted[i]]) continue;
           const cell = sorted[i], x = cells.p[cell][0], y = cells.p[cell][1];
           const s = spacing * gauss(1, .3, .2, 2, 2); // randomize to make placement not uniform
@@ -656,18 +657,19 @@
     const areaMean = d3.mean(valid.map(s => s.area)); // avarage state area
 
     // generic relations
-    for (let f=1; f < states.length; f++) {
+    let numberOfStates = states.length;
+    for (let f=1; f < numberOfStates; f++) {
       if (states[f].removed) continue;
 
       if (states[f].diplomacy.includes("Vassal")) {
         // Vassals copy relations from their Suzerains
         const suzerain = states[f].diplomacy.indexOf("Vassal");
 
-        for (let i=1; i < states.length; i++) {
+        for (let i=1; i < numberOfStates; i++) {
           if (i === f || i === suzerain) continue;
           states[f].diplomacy[i] = states[suzerain].diplomacy[i];
           if (states[suzerain].diplomacy[i] === "Suzerain") states[f].diplomacy[i] = "Ally";
-          for (let e=1; e < states.length; e++) {
+          for (let e=1; e < numberOfStates; e++) {
             if (e === f || e === suzerain) continue;
             if (states[e].diplomacy[suzerain] === "Suzerain" || states[e].diplomacy[suzerain] === "Vassal") continue;
             states[e].diplomacy[f] = states[e].diplomacy[suzerain];
@@ -676,7 +678,7 @@
         continue;
       }
 
-      for (let t=f+1; t < states.length; t++) {
+      for (let t=f+1; t < numberOfStates; t++) {
         if (states[t].removed) continue;
 
         if (states[t].diplomacy.includes("Vassal")) {
@@ -699,7 +701,7 @@
     }
 
     // declare wars
-    for (let attacker=1; attacker < states.length; attacker++) {
+    for (let attacker=1; attacker < numberOfStates; attacker++) {
       const ad = states[attacker].diplomacy; // attacker relations;
       if (states[attacker].removed) continue;
       if (!ad.includes("Rival")) continue; // no rivals to attack
diff --git a/modules/cultures-generator.js b/modules/cultures-generator.js
index 67763f7e..040cdd27 100644
--- a/modules/cultures-generator.js
+++ b/modules/cultures-generator.js
@@ -115,7 +115,8 @@
   function getCode(name) {
     const words = name.split(" "), letters = words.join("");
     let code = words.length === 2 ? words[0][0]+words[1][0] : letters.slice(0,2);
-    for (let i=1; i < letters.length-1 && pack.cultures.some(c => c.code === code); i++) {
+    let numberOfLetters = letters.length;
+    for (let i=1; i < numberOfLetters-1 && pack.cultures.some(c => c.code === code); i++) {
       code = letters[0] + letters[i].toUpperCase();
     }
     return code;
diff --git a/modules/names-generator.js b/modules/names-generator.js
index 32367be1..93375437 100644
--- a/modules/names-generator.js
+++ b/modules/names-generator.js
@@ -15,7 +15,8 @@
       const basic = !(/[^\u0000-\u007f]/.test(name)); // basic chars and English rules can be applied
 
       // split word into pseudo-syllables
-      for (let i=-1, syllable = ""; i < name.length; i += (syllable.length||1), syllable = "") {
+      let nameLength = name.length;
+      for (let i=-1, syllable = ""; i < nameLength; i += (syllable.length||1), syllable = "") {
         let prev = name[i] || ""; // pre-onset letter
         let v = 0; // 0 if no vowels in syllable
 
diff --git a/modules/ocean-layers.js b/modules/ocean-layers.js
index 50f4849c..7a230d05 100644
--- a/modules/ocean-layers.js
+++ b/modules/ocean-layers.js
@@ -66,7 +66,8 @@
 
   // Define grid ocean cells type based on distance form land
   function markupOcean(limits) {
-    for (let t = -2; t >= limits[0]-1; t--) {
+    let limits0 = limits[0];
+    for (let t = -2; t >= limits0-1; t--) {
       for (let i = 0; i < pointsN; i++) {
         if (cells.t[i] !== t+1) continue;
         cells.c[i].forEach(function(e) {if (!cells.t[e]) cells.t[e] = t;});
diff --git a/modules/religions-generator.js b/modules/religions-generator.js
index ee22e38e..e92757b3 100644
--- a/modules/religions-generator.js
+++ b/modules/religions-generator.js
@@ -13,7 +13,8 @@
   // turn weighted array into simple array
   const approaches = [];
   for (const a in approach) {
-    for (let j=0; j < approach[a]; j++) {
+    let approachA = approach[a];
+    for (let j=0; j < approachA; j++) {
       approaches.push(a);
     }
   }
@@ -295,7 +296,8 @@
     const name = rawName.replace("Old ", ""); // remove Old prefix
     const words = name.split(" "), letters = words.join("");
     let code = words.length === 2 ? words[0][0]+words[1][0] : letters.slice(0,2);
-    for (let i=1; i < letters.length-1 && pack.religions.some(r => r.code === code); i++) {
+    let numberOfLetters = letters.length;
+    for (let i=1; i < numberOfLetters-1 && pack.religions.some(r => r.code === code); i++) {
       code = letters[0] + letters[i].toUpperCase();
     }
     return code;
diff --git a/modules/river-generator.js b/modules/river-generator.js
index db799885..cc44610a 100644
--- a/modules/river-generator.js
+++ b/modules/river-generator.js
@@ -167,7 +167,8 @@
     const riverEnhanced = []; // to store enhanced segments
     let side = 1; // to control meandring direction
 
-    for (let s = 0; s < segments.length; s++) {
+    let numberOfSegments = segments.length;
+    for (let s = 0; s < numberOfSegments; s++) {
       const sX = segments[s].x, sY = segments[s].y; // segment start coordinates
       const c = pack.cells.conf[segments[s].cell] || 0; // if segment is river confluence
       riverEnhanced.push([sX, sY, c]);
diff --git a/modules/routes-generator.js b/modules/routes-generator.js
index 2e6d0159..74ce9b3d 100644
--- a/modules/routes-generator.js
+++ b/modules/routes-generator.js
@@ -70,13 +70,14 @@
 
     bodies.forEach(function(f) {
       const ports = allPorts.filter(b => b.port === f); // all ports on the same feature
-      if (ports.length < 2) return;
+      let numberOfPorts = ports.length;
+      if (numberOfPorts < 2) return;
 
-      for (let s=0; s < ports.length; s++) {
+      for (let s=0; s < numberOfPorts; s++) {
         const source = ports[s].cell;
         if (connected[source]) continue;
 
-        for (let t=s+1; t < ports.length; t++) {
+        for (let t=s+1; t < numberOfPorts; t++) {
           const target = ports[t].cell;
           if (connected[target]) continue;
 
diff --git a/modules/save-and-load.js b/modules/save-and-load.js
index 76f48efd..97b1660d 100644
--- a/modules/save-and-load.js
+++ b/modules/save-and-load.js
@@ -138,7 +138,8 @@ function inlineStyle(clone) {
     const compStyle = window.getComputedStyle(this);
     let style = "";
 
-    for (let i=0; i < compStyle.length; i++) {
+    let compStyleLength = compStyle.length;
+    for (let i=0; i < compStyleLength; i++) {
       const key = compStyle[i];
       const value = compStyle.getPropertyValue(key);
 
@@ -602,7 +603,8 @@ function parseLoadedData(data) {
       biomesData.name = biomes[2].split(",");
 
       // push custom biomes if any
-      for (let i=biomesData.i.length; i < biomesData.name.length; i++) {
+      let biomeNamesLength = biomesData.name.length;
+      for (let i=biomesData.i.length; i < biomeNamesLength; i++) {
         biomesData.i.push(biomesData.i.length);
         biomesData.iconsDensity.push(0);
         biomesData.icons.push([]);
diff --git a/modules/ui/burg-editor.js b/modules/ui/burg-editor.js
index 0691fa3e..03f074a7 100644
--- a/modules/ui/burg-editor.js
+++ b/modules/ui/burg-editor.js
@@ -181,7 +181,8 @@ function editBurg(id) {
     const basic = group.id === "cities" || group.id === "towns";
 
     const burgsInGroup = [];
-    for (let i=0; i < group.children.length; i++) {
+    let numberOfChildren = group.children.length;
+    for (let i=0; i < numberOfChildren; i++) {
       burgsInGroup.push(+group.children[i].dataset.id);
     }
     const burgsToRemove = burgsInGroup.filter(b => !pack.burgs[b].capital);
diff --git a/modules/ui/burgs-overview.js b/modules/ui/burgs-overview.js
index 35d668a6..13f1625e 100644
--- a/modules/ui/burgs-overview.js
+++ b/modules/ui/burgs-overview.js
@@ -422,12 +422,14 @@ function overviewBurgs() {
   function importBurgNames(dataLoaded) {
     if (!dataLoaded) {tip("Cannot load the file, please check the format", false, "error"); return;}
     const data = dataLoaded.split("\r\n");
-    if (!data.length) {tip("Cannot parse the list, please check the file format", false, "error"); return;}
+    let dataLength = data.length;
+    let numberOfBurgs = burgs.length;
+    if (!dataLength) {tip("Cannot parse the list, please check the file format", false, "error"); return;}
 
     let change = [], message = `Burgs will be renamed as below. Please confirm`;
     message += `<table class="overflow-table"><tr><th>Id</th><th>Current name</th><th>New Name</th></tr>`;
     const burgs = pack.burgs.filter(b => b.i && !b.removed);
-    for (let i=0; i < data.length && i <= burgs.length; i++) {
+    for (let i=0; i < dataLength && i <= numberOfBurgs; i++) {
       const v = data[i];
       if (!v || !burgs[i] || v == burgs[i].name) continue;
       change.push({id:burgs[i].i, name: v});
@@ -442,7 +444,8 @@ function overviewBurgs() {
       buttons: {
         Cancel: function() {$(this).dialog("close");},
         Confirm: function() {
-          for (let i=0; i < change.length; i++) {
+          let changeLength = change.length;
+          for (let i=0; i < changeLength; i++) {
             const id = change[i].id;
             pack.burgs[id].name = change[i].name;
             burgLabels.select("[data-id='" + id + "']").text(change[i].name);
diff --git a/modules/ui/editors.js b/modules/ui/editors.js
index 64e615c2..088329f5 100644
--- a/modules/ui/editors.js
+++ b/modules/ui/editors.js
@@ -620,7 +620,8 @@ function selectIcon(initial, callback) {
     ];
 
     let row = "";
-    for (let i=0; i < icons.length; i++) {
+    let numberOfIcons = icons.length;
+    for (let i=0; i < numberOfIcons; i++) {
       if (i%17 === 0) row = table.insertRow(i/17|0);
       const cell = row.insertCell(i%17);
       cell.innerHTML = icons[i];
diff --git a/modules/ui/elevation-profile.js b/modules/ui/elevation-profile.js
index f8b40d29..9ff0f0de 100644
--- a/modules/ui/elevation-profile.js
+++ b/modules/ui/elevation-profile.js
@@ -52,7 +52,8 @@ function showElevationProfile(data, routeLen, isRiver) {
   let lastBurgCell = 0;
   let burgCount = 0;
   let chartData = {biome:[], burg:[], cell:[], height:[], mi:1000000, ma:0, mih: 100, mah: 0, points:[]};
-  for (let i=0, prevB=0, prevH=-1; i  <data.length; i++) {
+  let dataLength = data.length;
+  for (let i=0, prevB=0, prevH=-1; i < dataLength; i++) {
     let cell = data[i];
     let h = pack.cells.h[cell];
     if (h < 20) h = 20;
@@ -93,7 +94,8 @@ function showElevationProfile(data, routeLen, isRiver) {
   function downloadCSV() {
     let data = "Point,X,Y,Cell,Height,Height value,Population,Burg,Burg population,Biome,Biome color,Culture,Culture color,Religion,Religion color,Province,Province color,State,State color\n"; // headers
 
-    for (let k=0; k < chartData.points.length; k++) {
+    let numberOfPoints = chartData.points.length;
+    for (let k=0; k < numberOfPoints; k++) {
       let cell = chartData.cell[k];
       let burg = pack.cells.burg[cell];
       let biome = pack.cells.biome[cell];
@@ -136,15 +138,16 @@ function showElevationProfile(data, routeLen, isRiver) {
   }
 
   function draw() {
+    let dataLength = data.length;
     chartData.points = [];
     let heightScale = 100 / parseInt(epScaleRange.value);
 
     heightScale *= .9; // curves cause the heights to go slightly higher, adjust here
 
-    const xscale = d3.scaleLinear().domain([0, data.length]).range([0, chartWidth]);
+    const xscale = d3.scaleLinear().domain([0, dataLength]).range([0, chartWidth]);
     const yscale = d3.scaleLinear().domain([0, chartData.ma * heightScale]).range([chartHeight, 0]);
 
-    for (let i=0; i<data.length; i++) {
+    for (let i=0; i < dataLength; i++) {
       chartData.points.push([xscale(i) + xOffset, yscale(chartData.height[i]) + yOffset]);
     }
 
@@ -157,12 +160,16 @@ function showElevationProfile(data, routeLen, isRiver) {
     let colors = getColorScheme();
     const landdef = chart.select("defs").append("linearGradient").attr("id", "landdef").attr("x1", "0%").attr("y1", "0%").attr("x2", "0%").attr("y2", "100%");
 
-    if (chartData.mah == chartData.mih) {
-      landdef.append("stop").attr("offset", "0%").attr("style", "stop-color:" + getColor(chartData.mih, colors) + ";stop-opacity:1");
-      landdef.append("stop").attr("offset", "100%").attr("style", "stop-color:" + getColor(chartData.mah, colors) + ";stop-opacity:1");
+    let mihChartData = chartData.mih;
+    let mahChartData = chartData.mah;
+
+    if (chartData.mah == mihChartData) {
+      landdef.append("stop").attr("offset", "0%").attr("style", "stop-color:" + getColor(mihChartData, colors) + ";stop-opacity:1");
+      landdef.append("stop").attr("offset", "100%").attr("style", "stop-color:" + getColor(mahChartData, colors) + ";stop-opacity:1");
     } else {
-      for (let k=chartData.mah; k >= chartData.mih; k--) {
-        let perc = 1 - (k - chartData.mih)  / (chartData.mah - chartData.mih);
+
+      for (let k=mahChartData; k >= mihChartData; k--) {
+        let perc = 1 - (k - mihChartData)  / (mahChartData - mihChartData);
         landdef.append("stop").attr("offset", perc*100 + "%").attr("style", "stop-color:" + getColor(k, colors) + ";stop-opacity:1");
       }
     }
@@ -263,13 +270,14 @@ function showElevationProfile(data, routeLen, isRiver) {
     const add = 15;
 
     let xwidth = chartData.points[1][0] - chartData.points[0][0];
-    for (let k=0; k<chartData.points.length; k++) {
+    let numberOfPoints = chartData.points.length;
+    for (let k=0; k < numberOfPoints; k++) {
       if (chartData.burg[k] > 0) {
         let b = chartData.burg[k];
 
         let x1 = chartData.points[k][0]; // left side of graph by default
         if (k > 0) x1 += xwidth/2; // center it if not first
-        if (k == chartData.points.length-1) x1 = chartWidth + xOffset; // right part of graph
+        if (k == numberOfPoints-1) x1 = chartWidth + xOffset; // right part of graph
         y1+=add;
         if (y1 >= yOffset) y1 = add;
 
diff --git a/modules/ui/layers.js b/modules/ui/layers.js
index 9be15346..4e32784d 100644
--- a/modules/ui/layers.js
+++ b/modules/ui/layers.js
@@ -728,7 +728,7 @@ function drawStates() {
     const chain = []; // vertices chain to form a path
     let land = vertices.c[start].some(c => cells.h[c] >= 20 && cells.state[c] !== t);
     function check(i) {state = cells.state[i]; land = cells.h[i] >= 20;}
-    
+
     for (let i=0, current = start; i === 0 || current !== start && i < 20000; i++) {
       const prev = chain[chain.length - 1] ? chain[chain.length - 1][0] : -1; // previous vertex in chain
       chain.push([current, state, land]); // add current vertex to sequence
@@ -760,7 +760,7 @@ function drawBorders() {
   const sUsed = new Array(pack.states.length).fill("").map(a => []);
   const pUsed = new Array(pack.provinces.length).fill("").map(a => []);
 
-  for (let i=0; i < cells.i.length; i++) {
+  for (let i=0; i < n; i++) {
     if (!cells.state[i]) continue;
     const p = cells.province[i];
     const s = cells.state[i];
diff --git a/modules/ui/options.js b/modules/ui/options.js
index 60eed024..c461e59d 100644
--- a/modules/ui/options.js
+++ b/modules/ui/options.js
@@ -295,7 +295,8 @@ function applyStoredOptions() {
   if (localStorage.getItem("distanceUnit")) applyOption(distanceUnitInput, localStorage.getItem("distanceUnit"));
   if (localStorage.getItem("heightUnit")) applyOption(heightUnit, localStorage.getItem("heightUnit"));
 
-  for (let i=0; i < localStorage.length; i++) {
+  let localStorageLength = localStorage.length;
+  for (let i=0; i < localStorageLength; i++) {
     const stored = localStorage.key(i), value = localStorage.getItem(stored);
     const input = document.getElementById(stored+"Input") || document.getElementById(stored);
     const output = document.getElementById(stored+"Output");
diff --git a/modules/ui/style.js b/modules/ui/style.js
index 2cb1dcaf..db85fe8a 100644
--- a/modules/ui/style.js
+++ b/modules/ui/style.js
@@ -1111,7 +1111,8 @@ function addFonts(url) {
 // Update font list for Label and Burg Editors
 function updateFontOptions() {
   styleSelectFont.innerHTML = "";
-  for (let i=0; i < fonts.length; i++) {
+  let numberOfFonts = fonts.length;
+  for (let i=0; i < numberOfFonts; i++) {
     const opt = document.createElement('option');
     opt.value = i;
     const font = fonts[i].split(':')[0].replace(/\+/g, " ");
diff --git a/modules/ui/tools.js b/modules/ui/tools.js
index 066eda0b..0f1a14e7 100644
--- a/modules/ui/tools.js
+++ b/modules/ui/tools.js
@@ -109,7 +109,8 @@ function regenerateBurgs() {
   const burgsCount = manorsInput.value == 1000 ? rn(sorted.length / 5 / (grid.points.length / 10000) ** .8) + states.length : +manorsInput.value + states.length;
   const spacing = (graphWidth + graphHeight) / 150 / (burgsCount ** .7 / 66); // base min distance between towns
 
-  for (let i=0; i < sorted.length && burgs.length < burgsCount; i++) {
+  let sortedLength = sorted.length;
+  for (let i=0; i < sortedLength && burgs.length < burgsCount; i++) {
     const id = burgs.length;
     const cell = sorted[i];
     const x = cells.p[cell][0], y = cells.p[cell][1];
diff --git a/modules/utils.js b/modules/utils.js
index 3c8d5f6a..50d768fb 100644
--- a/modules/utils.js
+++ b/modules/utils.js
@@ -457,7 +457,8 @@ function ra(array) {
 function rw(object) {
   const array = [];
   for (const key in object) {
-    for (let i=0; i < object[key]; i++) {
+    let objectKey = object[key];
+    for (let i=0; i < objectKey; i++) {
       array.push(key);
     }
   };
diff --git a/modules/voronoi.js b/modules/voronoi.js
index f7b82292..ba0d29ac 100644
--- a/modules/voronoi.js
+++ b/modules/voronoi.js
@@ -8,7 +8,8 @@
     const cells = {v: [], c: [], b: []}; // voronoi cells: v = cell vertices, c = adjacent cells, b = near-border cell
     const vertices = {p: [], v: [], c: []}; // cells vertices: p = vertex coordinates, v = neighboring vertices, c = adjacent cells
 
-    for (let e=0; e < delaunay.triangles.length; e++) {
+    var triangles = delaunay.triangles.length;
+    for (let e=0; e < triangles; e++) {
 
       const p = delaunay.triangles[nextHalfedge(e)];
       if (p < pointsN && !cells.c[p]) {
@@ -67,13 +68,15 @@
   function prevHalfedge(e) {return (e % 3 === 0) ? e+2 : e-1;}
 
   function circumcenter(a, b, c) {
-    let ad = a[0]*a[0] + a[1]*a[1],
-        bd = b[0]*b[0] + b[1]*b[1],
-        cd = c[0]*c[0] + c[1]*c[1];
-    let D = 2 * (a[0] * (b[1] - c[1]) + b[0] * (c[1] - a[1]) + c[0] * (a[1] - b[1]));
+    let a0 = a[0], b0 = b[0], c0 = c[0],
+        a1 = a[1], b1 = b[1], c1 = c[1];
+    let ad = a0*a0 + a1*a1,
+        bd = b0*b0 + b1*b1,
+        cd = c0*c0 + c1*c1;
+    let D = 2 * (a0 * (b1 - c1) + b0 * (c1 - a1) + c0 * (a1 - b1));
     return [
-      Math.floor(1/D * (ad * (b[1] - c[1]) + bd * (c[1] - a[1]) + cd * (a[1] - b[1]))),
-      Math.floor(1/D * (ad * (c[0] - b[0]) + bd * (a[0] - c[0]) + cd * (b[0] - a[0])))
+      Math.floor(1/D * (ad * (b1 - c1) + bd * (c1 - a1) + cd * (a1 - b1))),
+      Math.floor(1/D * (ad * (c0 - b0) + bd * (a0 - c0) + cd * (b0 - a0)))
     ];
   }