diff --git a/src/ol/extent.js b/src/ol/extent.js
index 3091ad7a12..b90eaf9006 100644
--- a/src/ol/extent.js
+++ b/src/ol/extent.js
@@ -340,8 +340,7 @@ export function extendCoordinate(extent, coordinate) {
  * @return {ol.Extent} Extent.
  */
 export function extendCoordinates(extent, coordinates) {
-  let i, ii;
-  for (i = 0, ii = coordinates.length; i < ii; ++i) {
+  for (let i = 0, ii = coordinates.length; i < ii; ++i) {
     extendCoordinate(extent, coordinates[i]);
   }
   return extent;
@@ -370,8 +369,7 @@ export function extendFlatCoordinates(extent, flatCoordinates, offset, end, stri
  * @return {ol.Extent} Extent.
  */
 export function extendRings(extent, rings) {
-  let i, ii;
-  for (i = 0, ii = rings.length; i < ii; ++i) {
+  for (let i = 0, ii = rings.length; i < ii; ++i) {
     extendCoordinates(extent, rings[i]);
   }
   return extent;
diff --git a/src/ol/geom/GeometryCollection.js b/src/ol/geom/GeometryCollection.js
index 4294fda6df..5fc11ea021 100644
--- a/src/ol/geom/GeometryCollection.js
+++ b/src/ol/geom/GeometryCollection.js
@@ -41,8 +41,7 @@ inherits(GeometryCollection, Geometry);
  */
 GeometryCollection.cloneGeometries_ = function(geometries) {
   const clonedGeometries = [];
-  let i, ii;
-  for (i = 0, ii = geometries.length; i < ii; ++i) {
+  for (let i = 0, ii = geometries.length; i < ii; ++i) {
     clonedGeometries.push(geometries[i].clone());
   }
   return clonedGeometries;
@@ -53,11 +52,10 @@ GeometryCollection.cloneGeometries_ = function(geometries) {
  * @private
  */
 GeometryCollection.prototype.unlistenGeometriesChange_ = function() {
-  let i, ii;
   if (!this.geometries_) {
     return;
   }
-  for (i = 0, ii = this.geometries_.length; i < ii; ++i) {
+  for (let i = 0, ii = this.geometries_.length; i < ii; ++i) {
     _ol_events_.unlisten(
       this.geometries_[i], EventType.CHANGE,
       this.changed, this);
@@ -69,11 +67,10 @@ GeometryCollection.prototype.unlistenGeometriesChange_ = function() {
  * @private
  */
 GeometryCollection.prototype.listenGeometriesChange_ = function() {
-  let i, ii;
   if (!this.geometries_) {
     return;
   }
-  for (i = 0, ii = this.geometries_.length; i < ii; ++i) {
+  for (let i = 0, ii = this.geometries_.length; i < ii; ++i) {
     _ol_events_.listen(
       this.geometries_[i], EventType.CHANGE,
       this.changed, this);
@@ -102,8 +99,7 @@ GeometryCollection.prototype.closestPointXY = function(x, y, closestPoint, minSq
     return minSquaredDistance;
   }
   const geometries = this.geometries_;
-  let i, ii;
-  for (i = 0, ii = geometries.length; i < ii; ++i) {
+  for (let i = 0, ii = geometries.length; i < ii; ++i) {
     minSquaredDistance = geometries[i].closestPointXY(
       x, y, closestPoint, minSquaredDistance);
   }
@@ -116,8 +112,7 @@ GeometryCollection.prototype.closestPointXY = function(x, y, closestPoint, minSq
  */
 GeometryCollection.prototype.containsXY = function(x, y) {
   const geometries = this.geometries_;
-  let i, ii;
-  for (i = 0, ii = geometries.length; i < ii; ++i) {
+  for (let i = 0, ii = geometries.length; i < ii; ++i) {
     if (geometries[i].containsXY(x, y)) {
       return true;
     }
@@ -178,8 +173,7 @@ GeometryCollection.prototype.getSimplifiedGeometry = function(squaredTolerance)
     const simplifiedGeometries = [];
     const geometries = this.geometries_;
     let simplified = false;
-    let i, ii;
-    for (i = 0, ii = geometries.length; i < ii; ++i) {
+    for (let i = 0, ii = geometries.length; i < ii; ++i) {
       const geometry = geometries[i];
       const simplifiedGeometry = geometry.getSimplifiedGeometry(squaredTolerance);
       simplifiedGeometries.push(simplifiedGeometry);
@@ -215,8 +209,7 @@ GeometryCollection.prototype.getType = function() {
  */
 GeometryCollection.prototype.intersectsExtent = function(extent) {
   const geometries = this.geometries_;
-  let i, ii;
-  for (i = 0, ii = geometries.length; i < ii; ++i) {
+  for (let i = 0, ii = geometries.length; i < ii; ++i) {
     if (geometries[i].intersectsExtent(extent)) {
       return true;
     }
@@ -291,8 +284,7 @@ GeometryCollection.prototype.setGeometriesArray = function(geometries) {
  */
 GeometryCollection.prototype.applyTransform = function(transformFn) {
   const geometries = this.geometries_;
-  let i, ii;
-  for (i = 0, ii = geometries.length; i < ii; ++i) {
+  for (let i = 0, ii = geometries.length; i < ii; ++i) {
     geometries[i].applyTransform(transformFn);
   }
   this.changed();
@@ -308,8 +300,7 @@ GeometryCollection.prototype.applyTransform = function(transformFn) {
  */
 GeometryCollection.prototype.translate = function(deltaX, deltaY) {
   const geometries = this.geometries_;
-  let i, ii;
-  for (i = 0, ii = geometries.length; i < ii; ++i) {
+  for (let i = 0, ii = geometries.length; i < ii; ++i) {
     geometries[i].translate(deltaX, deltaY);
   }
   this.changed();
diff --git a/src/ol/geom/MultiLineString.js b/src/ol/geom/MultiLineString.js
index 283aac83df..2a4e05cf71 100644
--- a/src/ol/geom/MultiLineString.js
+++ b/src/ol/geom/MultiLineString.js
@@ -186,8 +186,7 @@ MultiLineString.prototype.getLineStrings = function() {
   /** @type {Array.<ol.geom.LineString>} */
   const lineStrings = [];
   let offset = 0;
-  let i, ii;
-  for (i = 0, ii = ends.length; i < ii; ++i) {
+  for (let i = 0, ii = ends.length; i < ii; ++i) {
     const end = ends[i];
     const lineString = new LineString(null);
     lineString.setFlatCoordinates(layout, flatCoordinates.slice(offset, end));
@@ -207,8 +206,7 @@ MultiLineString.prototype.getFlatMidpoints = function() {
   let offset = 0;
   const ends = this.ends_;
   const stride = this.stride;
-  let i, ii;
-  for (i = 0, ii = ends.length; i < ii; ++i) {
+  for (let i = 0, ii = ends.length; i < ii; ++i) {
     const end = ends[i];
     const midpoint = _ol_geom_flat_interpolate_.lineString(
       flatCoordinates, offset, end, stride, 0.5);
@@ -296,8 +294,7 @@ MultiLineString.prototype.setLineStrings = function(lineStrings) {
   let layout = this.getLayout();
   const flatCoordinates = [];
   const ends = [];
-  let i, ii;
-  for (i = 0, ii = lineStrings.length; i < ii; ++i) {
+  for (let i = 0, ii = lineStrings.length; i < ii; ++i) {
     const lineString = lineStrings[i];
     if (i === 0) {
       layout = lineString.getLayout();
diff --git a/src/ol/geom/MultiPoint.js b/src/ol/geom/MultiPoint.js
index 29b3e13987..a975a36da9 100644
--- a/src/ol/geom/MultiPoint.js
+++ b/src/ol/geom/MultiPoint.js
@@ -67,13 +67,12 @@ MultiPoint.prototype.closestPointXY = function(x, y, closestPoint, minSquaredDis
   }
   const flatCoordinates = this.flatCoordinates;
   const stride = this.stride;
-  let i, ii, j;
-  for (i = 0, ii = flatCoordinates.length; i < ii; i += stride) {
+  for (let i = 0, ii = flatCoordinates.length; i < ii; i += stride) {
     const squaredDistance = squaredDx(
       x, y, flatCoordinates[i], flatCoordinates[i + 1]);
     if (squaredDistance < minSquaredDistance) {
       minSquaredDistance = squaredDistance;
-      for (j = 0; j < stride; ++j) {
+      for (let j = 0; j < stride; ++j) {
         closestPoint[j] = flatCoordinates[i + j];
       }
       closestPoint.length = stride;
@@ -102,8 +101,7 @@ MultiPoint.prototype.getCoordinates = function() {
  * @api
  */
 MultiPoint.prototype.getPoint = function(index) {
-  const n = !this.flatCoordinates ?
-    0 : this.flatCoordinates.length / this.stride;
+  const n = !this.flatCoordinates ? 0 : this.flatCoordinates.length / this.stride;
   if (index < 0 || n <= index) {
     return null;
   }
@@ -125,8 +123,7 @@ MultiPoint.prototype.getPoints = function() {
   const stride = this.stride;
   /** @type {Array.<ol.geom.Point>} */
   const points = [];
-  let i, ii;
-  for (i = 0, ii = flatCoordinates.length; i < ii; i += stride) {
+  for (let i = 0, ii = flatCoordinates.length; i < ii; i += stride) {
     const point = new Point(null);
     point.setFlatCoordinates(layout, flatCoordinates.slice(i, i + stride));
     points.push(point);
@@ -151,10 +148,9 @@ MultiPoint.prototype.getType = function() {
 MultiPoint.prototype.intersectsExtent = function(extent) {
   const flatCoordinates = this.flatCoordinates;
   const stride = this.stride;
-  let i, ii, x, y;
-  for (i = 0, ii = flatCoordinates.length; i < ii; i += stride) {
-    x = flatCoordinates[i];
-    y = flatCoordinates[i + 1];
+  for (let i = 0, ii = flatCoordinates.length; i < ii; i += stride) {
+    const x = flatCoordinates[i];
+    const y = flatCoordinates[i + 1];
     if (containsXY(extent, x, y)) {
       return true;
     }
diff --git a/src/ol/geom/MultiPolygon.js b/src/ol/geom/MultiPolygon.js
index c2f7bab8cd..f01b88d955 100644
--- a/src/ol/geom/MultiPolygon.js
+++ b/src/ol/geom/MultiPolygon.js
@@ -99,8 +99,7 @@ MultiPolygon.prototype.appendPolygon = function(polygon) {
     const offset = this.flatCoordinates.length;
     extend(this.flatCoordinates, polygon.getFlatCoordinates());
     ends = polygon.getEnds().slice();
-    let i, ii;
-    for (i = 0, ii = ends.length; i < ii; ++i) {
+    for (let i = 0, ii = ends.length; i < ii; ++i) {
       ends[i] += offset;
     }
   }
@@ -293,8 +292,7 @@ MultiPolygon.prototype.getPolygon = function(index) {
   const ends = this.endss_[index].slice();
   const end = ends[ends.length - 1];
   if (offset !== 0) {
-    let i, ii;
-    for (i = 0, ii = ends.length; i < ii; ++i) {
+    for (let i = 0, ii = ends.length; i < ii; ++i) {
       ends[i] -= offset;
     }
   }
@@ -316,12 +314,11 @@ MultiPolygon.prototype.getPolygons = function() {
   const endss = this.endss_;
   const polygons = [];
   let offset = 0;
-  let i, ii, j, jj;
-  for (i = 0, ii = endss.length; i < ii; ++i) {
+  for (let i = 0, ii = endss.length; i < ii; ++i) {
     const ends = endss[i].slice();
     const end = ends[ends.length - 1];
     if (offset !== 0) {
-      for (j = 0, jj = ends.length; j < jj; ++j) {
+      for (let j = 0, jj = ends.length; j < jj; ++j) {
         ends[j] -= offset;
       }
     }
diff --git a/src/ol/geom/SimpleGeometry.js b/src/ol/geom/SimpleGeometry.js
index 409f490597..97e6dc1047 100644
--- a/src/ol/geom/SimpleGeometry.js
+++ b/src/ol/geom/SimpleGeometry.js
@@ -230,8 +230,7 @@ SimpleGeometry.prototype.setLayout = function(layout, coordinates, nesting) {
   if (layout) {
     stride = getStrideForLayout(layout);
   } else {
-    let i;
-    for (i = 0; i < nesting; ++i) {
+    for (let i = 0; i < nesting; ++i) {
       if (coordinates.length === 0) {
         this.layout = GeometryLayout.XY;
         this.stride = 2;
diff --git a/src/ol/geom/flat/center.js b/src/ol/geom/flat/center.js
index e86a523c0c..27887f37d5 100644
--- a/src/ol/geom/flat/center.js
+++ b/src/ol/geom/flat/center.js
@@ -14,9 +14,8 @@ const _ol_geom_flat_center_ = {};
  */
 _ol_geom_flat_center_.linearRingss = function(flatCoordinates, offset, endss, stride) {
   const flatCenters = [];
-  let i, ii;
   let extent = createEmpty();
-  for (i = 0, ii = endss.length; i < ii; ++i) {
+  for (let i = 0, ii = endss.length; i < ii; ++i) {
     const ends = endss[i];
     extent = createOrUpdateFromFlatCoordinates(flatCoordinates, offset, ends[0], stride);
     flatCenters.push((extent[0] + extent[2]) / 2, (extent[1] + extent[3]) / 2);
diff --git a/src/ol/geom/flat/closest.js b/src/ol/geom/flat/closest.js
index 02ac2a1102..12d5802592 100644
--- a/src/ol/geom/flat/closest.js
+++ b/src/ol/geom/flat/closest.js
@@ -22,7 +22,7 @@ _ol_geom_flat_closest_.point = function(flatCoordinates, offset1, offset2, strid
   const y1 = flatCoordinates[offset1 + 1];
   const dx = flatCoordinates[offset2] - x1;
   const dy = flatCoordinates[offset2 + 1] - y1;
-  let i, offset;
+  let offset;
   if (dx === 0 && dy === 0) {
     offset = offset1;
   } else {
@@ -30,7 +30,7 @@ _ol_geom_flat_closest_.point = function(flatCoordinates, offset1, offset2, strid
     if (t > 1) {
       offset = offset2;
     } else if (t > 0) {
-      for (i = 0; i < stride; ++i) {
+      for (let i = 0; i < stride; ++i) {
         closestPoint[i] = lerp(flatCoordinates[offset1 + i],
           flatCoordinates[offset2 + i], t);
       }
@@ -40,7 +40,7 @@ _ol_geom_flat_closest_.point = function(flatCoordinates, offset1, offset2, strid
       offset = offset1;
     }
   }
-  for (i = 0; i < stride; ++i) {
+  for (let i = 0; i < stride; ++i) {
     closestPoint[i] = flatCoordinates[offset + i];
   }
   closestPoint.length = stride;
@@ -83,8 +83,7 @@ _ol_geom_flat_closest_.getMaxSquaredDelta = function(flatCoordinates, offset, en
  * @return {number} Max squared delta.
  */
 _ol_geom_flat_closest_.getsMaxSquaredDelta = function(flatCoordinates, offset, ends, stride, maxSquaredDelta) {
-  let i, ii;
-  for (i = 0, ii = ends.length; i < ii; ++i) {
+  for (let i = 0, ii = ends.length; i < ii; ++i) {
     const end = ends[i];
     maxSquaredDelta = _ol_geom_flat_closest_.getMaxSquaredDelta(
       flatCoordinates, offset, end, stride, maxSquaredDelta);
@@ -103,8 +102,7 @@ _ol_geom_flat_closest_.getsMaxSquaredDelta = function(flatCoordinates, offset, e
  * @return {number} Max squared delta.
  */
 _ol_geom_flat_closest_.getssMaxSquaredDelta = function(flatCoordinates, offset, endss, stride, maxSquaredDelta) {
-  let i, ii;
-  for (i = 0, ii = endss.length; i < ii; ++i) {
+  for (let i = 0, ii = endss.length; i < ii; ++i) {
     const ends = endss[i];
     maxSquaredDelta = _ol_geom_flat_closest_.getsMaxSquaredDelta(
       flatCoordinates, offset, ends, stride, maxSquaredDelta);
@@ -213,8 +211,7 @@ _ol_geom_flat_closest_.getsClosestPoint = function(flatCoordinates, offset, ends
   stride, maxDelta, isRing, x, y, closestPoint, minSquaredDistance,
   opt_tmpPoint) {
   const tmpPoint = opt_tmpPoint ? opt_tmpPoint : [NaN, NaN];
-  let i, ii;
-  for (i = 0, ii = ends.length; i < ii; ++i) {
+  for (let i = 0, ii = ends.length; i < ii; ++i) {
     const end = ends[i];
     minSquaredDistance = _ol_geom_flat_closest_.getClosestPoint(
       flatCoordinates, offset, end, stride,
@@ -243,8 +240,7 @@ _ol_geom_flat_closest_.getssClosestPoint = function(flatCoordinates, offset,
   endss, stride, maxDelta, isRing, x, y, closestPoint, minSquaredDistance,
   opt_tmpPoint) {
   const tmpPoint = opt_tmpPoint ? opt_tmpPoint : [NaN, NaN];
-  let i, ii;
-  for (i = 0, ii = endss.length; i < ii; ++i) {
+  for (let i = 0, ii = endss.length; i < ii; ++i) {
     const ends = endss[i];
     minSquaredDistance = _ol_geom_flat_closest_.getsClosestPoint(
       flatCoordinates, offset, ends, stride,
diff --git a/src/ol/geom/flat/contains.js b/src/ol/geom/flat/contains.js
index 00d72acfb2..cd4c54bf8b 100644
--- a/src/ol/geom/flat/contains.js
+++ b/src/ol/geom/flat/contains.js
@@ -81,8 +81,7 @@ _ol_geom_flat_contains_.linearRingsContainsXY = function(flatCoordinates, offset
     flatCoordinates, offset, ends[0], stride, x, y)) {
     return false;
   }
-  let i, ii;
-  for (i = 1, ii = ends.length; i < ii; ++i) {
+  for (let i = 1, ii = ends.length; i < ii; ++i) {
     if (_ol_geom_flat_contains_.linearRingContainsXY(
       flatCoordinates, ends[i - 1], ends[i], stride, x, y)) {
       return false;
@@ -105,8 +104,7 @@ _ol_geom_flat_contains_.linearRingssContainsXY = function(flatCoordinates, offse
   if (endss.length === 0) {
     return false;
   }
-  let i, ii;
-  for (i = 0, ii = endss.length; i < ii; ++i) {
+  for (let i = 0, ii = endss.length; i < ii; ++i) {
     const ends = endss[i];
     if (_ol_geom_flat_contains_.linearRingsContainsXY(
       flatCoordinates, offset, ends, stride, x, y)) {
diff --git a/src/ol/geom/flat/deflate.js b/src/ol/geom/flat/deflate.js
index 52f318a2d1..71539a5dca 100644
--- a/src/ol/geom/flat/deflate.js
+++ b/src/ol/geom/flat/deflate.js
@@ -12,8 +12,7 @@ const _ol_geom_flat_deflate_ = {};
  * @return {number} offset Offset.
  */
 _ol_geom_flat_deflate_.coordinate = function(flatCoordinates, offset, coordinate, stride) {
-  let i, ii;
-  for (i = 0, ii = coordinate.length; i < ii; ++i) {
+  for (let i = 0, ii = coordinate.length; i < ii; ++i) {
     flatCoordinates[offset++] = coordinate[i];
   }
   return offset;
@@ -28,8 +27,7 @@ _ol_geom_flat_deflate_.coordinate = function(flatCoordinates, offset, coordinate
  * @return {number} offset Offset.
  */
 _ol_geom_flat_deflate_.coordinates = function(flatCoordinates, offset, coordinates, stride) {
-  let i, ii;
-  for (i = 0, ii = coordinates.length; i < ii; ++i) {
+  for (let i = 0, ii = coordinates.length; i < ii; ++i) {
     const coordinate = coordinates[i];
     for (let j = 0; j < stride; ++j) {
       flatCoordinates[offset++] = coordinate[j];
@@ -50,8 +48,7 @@ _ol_geom_flat_deflate_.coordinates = function(flatCoordinates, offset, coordinat
 _ol_geom_flat_deflate_.coordinatess = function(flatCoordinates, offset, coordinatess, stride, opt_ends) {
   const ends = opt_ends ? opt_ends : [];
   let i = 0;
-  let j, jj;
-  for (j = 0, jj = coordinatess.length; j < jj; ++j) {
+  for (let j = 0, jj = coordinatess.length; j < jj; ++j) {
     const end = _ol_geom_flat_deflate_.coordinates(
       flatCoordinates, offset, coordinatess[j], stride);
     ends[i++] = end;
@@ -73,8 +70,7 @@ _ol_geom_flat_deflate_.coordinatess = function(flatCoordinates, offset, coordina
 _ol_geom_flat_deflate_.coordinatesss = function(flatCoordinates, offset, coordinatesss, stride, opt_endss) {
   const endss = opt_endss ? opt_endss : [];
   let i = 0;
-  let j, jj;
-  for (j = 0, jj = coordinatesss.length; j < jj; ++j) {
+  for (let j = 0, jj = coordinatesss.length; j < jj; ++j) {
     const ends = _ol_geom_flat_deflate_.coordinatess(
       flatCoordinates, offset, coordinatesss[j], stride, endss[i]);
     endss[i++] = ends;
diff --git a/src/ol/geom/flat/inflate.js b/src/ol/geom/flat/inflate.js
index bbe7102a29..b95296c88c 100644
--- a/src/ol/geom/flat/inflate.js
+++ b/src/ol/geom/flat/inflate.js
@@ -15,8 +15,7 @@ const _ol_geom_flat_inflate_ = {};
 _ol_geom_flat_inflate_.coordinates = function(flatCoordinates, offset, end, stride, opt_coordinates) {
   const coordinates = opt_coordinates !== undefined ? opt_coordinates : [];
   let i = 0;
-  let j;
-  for (j = offset; j < end; j += stride) {
+  for (let j = offset; j < end; j += stride) {
     coordinates[i++] = flatCoordinates.slice(j, j + stride);
   }
   coordinates.length = i;
@@ -35,8 +34,7 @@ _ol_geom_flat_inflate_.coordinates = function(flatCoordinates, offset, end, stri
 _ol_geom_flat_inflate_.coordinatess = function(flatCoordinates, offset, ends, stride, opt_coordinatess) {
   const coordinatess = opt_coordinatess !== undefined ? opt_coordinatess : [];
   let i = 0;
-  let j, jj;
-  for (j = 0, jj = ends.length; j < jj; ++j) {
+  for (let j = 0, jj = ends.length; j < jj; ++j) {
     const end = ends[j];
     coordinatess[i++] = _ol_geom_flat_inflate_.coordinates(
       flatCoordinates, offset, end, stride, coordinatess[i]);
@@ -59,8 +57,7 @@ _ol_geom_flat_inflate_.coordinatess = function(flatCoordinates, offset, ends, st
 _ol_geom_flat_inflate_.coordinatesss = function(flatCoordinates, offset, endss, stride, opt_coordinatesss) {
   const coordinatesss = opt_coordinatesss !== undefined ? opt_coordinatesss : [];
   let i = 0;
-  let j, jj;
-  for (j = 0, jj = endss.length; j < jj; ++j) {
+  for (let j = 0, jj = endss.length; j < jj; ++j) {
     const ends = endss[j];
     coordinatesss[i++] = _ol_geom_flat_inflate_.coordinatess(
       flatCoordinates, offset, ends, stride, coordinatesss[i]);
diff --git a/src/ol/geom/flat/interiorpoint.js b/src/ol/geom/flat/interiorpoint.js
index 079f154768..1c189648f9 100644
--- a/src/ol/geom/flat/interiorpoint.js
+++ b/src/ol/geom/flat/interiorpoint.js
@@ -85,8 +85,7 @@ _ol_geom_flat_interiorpoint_.linearRings = function(flatCoordinates, offset,
  */
 _ol_geom_flat_interiorpoint_.linearRingss = function(flatCoordinates, offset, endss, stride, flatCenters) {
   let interiorPoints = [];
-  let i, ii;
-  for (i = 0, ii = endss.length; i < ii; ++i) {
+  for (let i = 0, ii = endss.length; i < ii; ++i) {
     const ends = endss[i];
     interiorPoints = _ol_geom_flat_interiorpoint_.linearRings(flatCoordinates,
       offset, ends, stride, flatCenters, 2 * i, interiorPoints);
diff --git a/src/ol/geom/flat/intersectsextent.js b/src/ol/geom/flat/intersectsextent.js
index b632820fdf..911743f282 100644
--- a/src/ol/geom/flat/intersectsextent.js
+++ b/src/ol/geom/flat/intersectsextent.js
@@ -54,8 +54,7 @@ _ol_geom_flat_intersectsextent_.lineString = function(flatCoordinates, offset, e
  * @return {boolean} True if the geometry and the extent intersect.
  */
 _ol_geom_flat_intersectsextent_.lineStrings = function(flatCoordinates, offset, ends, stride, extent) {
-  let i, ii;
-  for (i = 0, ii = ends.length; i < ii; ++i) {
+  for (let i = 0, ii = ends.length; i < ii; ++i) {
     if (_ol_geom_flat_intersectsextent_.lineString(
       flatCoordinates, offset, ends[i], stride, extent)) {
       return true;
@@ -115,8 +114,7 @@ _ol_geom_flat_intersectsextent_.linearRings = function(flatCoordinates, offset,
   if (ends.length === 1) {
     return true;
   }
-  let i, ii;
-  for (i = 1, ii = ends.length; i < ii; ++i) {
+  for (let i = 1, ii = ends.length; i < ii; ++i) {
     if (_ol_geom_flat_contains_.linearRingContainsExtent(
       flatCoordinates, ends[i - 1], ends[i], stride, extent)) {
       return false;
@@ -135,8 +133,7 @@ _ol_geom_flat_intersectsextent_.linearRings = function(flatCoordinates, offset,
  * @return {boolean} True if the geometry and the extent intersect.
  */
 _ol_geom_flat_intersectsextent_.linearRingss = function(flatCoordinates, offset, endss, stride, extent) {
-  let i, ii;
-  for (i = 0, ii = endss.length; i < ii; ++i) {
+  for (let i = 0, ii = endss.length; i < ii; ++i) {
     const ends = endss[i];
     if (_ol_geom_flat_intersectsextent_.linearRings(
       flatCoordinates, offset, ends, stride, extent)) {
diff --git a/src/ol/geom/flat/length.js b/src/ol/geom/flat/length.js
index 1dde4b171a..c1139211a4 100644
--- a/src/ol/geom/flat/length.js
+++ b/src/ol/geom/flat/length.js
@@ -15,8 +15,7 @@ _ol_geom_flat_length_.lineString = function(flatCoordinates, offset, end, stride
   let x1 = flatCoordinates[offset];
   let y1 = flatCoordinates[offset + 1];
   let length = 0;
-  let i;
-  for (i = offset + stride; i < end; i += stride) {
+  for (let i = offset + stride; i < end; i += stride) {
     const x2 = flatCoordinates[i];
     const y2 = flatCoordinates[i + 1];
     length += Math.sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
@@ -35,8 +34,7 @@ _ol_geom_flat_length_.lineString = function(flatCoordinates, offset, end, stride
  * @return {number} Perimeter.
  */
 _ol_geom_flat_length_.linearRing = function(flatCoordinates, offset, end, stride) {
-  let perimeter =
-      _ol_geom_flat_length_.lineString(flatCoordinates, offset, end, stride);
+  let perimeter = _ol_geom_flat_length_.lineString(flatCoordinates, offset, end, stride);
   const dx = flatCoordinates[end - stride] - flatCoordinates[offset];
   const dy = flatCoordinates[end - stride + 1] - flatCoordinates[offset + 1];
   perimeter += Math.sqrt(dx * dx + dy * dy);
diff --git a/src/ol/geom/flat/simplify.js b/src/ol/geom/flat/simplify.js
index 972a5f1fcd..a9928896a3 100644
--- a/src/ol/geom/flat/simplify.js
+++ b/src/ol/geom/flat/simplify.js
@@ -91,7 +91,6 @@ _ol_geom_flat_simplify_.douglasPeucker = function(flatCoordinates, offset, end,
   /** @type {Array.<number>} */
   const stack = [offset, end - stride];
   let index = 0;
-  let i;
   while (stack.length > 0) {
     const last = stack.pop();
     const first = stack.pop();
@@ -100,7 +99,7 @@ _ol_geom_flat_simplify_.douglasPeucker = function(flatCoordinates, offset, end,
     const y1 = flatCoordinates[first + 1];
     const x2 = flatCoordinates[last];
     const y2 = flatCoordinates[last + 1];
-    for (i = first + stride; i < last; i += stride) {
+    for (let i = first + stride; i < last; i += stride) {
       const x = flatCoordinates[i];
       const y = flatCoordinates[i + 1];
       const squaredDistance = squaredSegmentDistance(
@@ -120,7 +119,7 @@ _ol_geom_flat_simplify_.douglasPeucker = function(flatCoordinates, offset, end,
       }
     }
   }
-  for (i = 0; i < n; ++i) {
+  for (let i = 0; i < n; ++i) {
     if (markers[i]) {
       simplifiedFlatCoordinates[simplifiedOffset++] =
           flatCoordinates[offset + i * stride];
@@ -147,8 +146,7 @@ _ol_geom_flat_simplify_.douglasPeucker = function(flatCoordinates, offset, end,
 _ol_geom_flat_simplify_.douglasPeuckers = function(flatCoordinates, offset,
   ends, stride, squaredTolerance, simplifiedFlatCoordinates,
   simplifiedOffset, simplifiedEnds) {
-  let i, ii;
-  for (i = 0, ii = ends.length; i < ii; ++i) {
+  for (let i = 0, ii = ends.length; i < ii; ++i) {
     const end = ends[i];
     simplifiedOffset = _ol_geom_flat_simplify_.douglasPeucker(
       flatCoordinates, offset, end, stride, squaredTolerance,
@@ -175,8 +173,7 @@ _ol_geom_flat_simplify_.douglasPeuckers = function(flatCoordinates, offset,
 _ol_geom_flat_simplify_.douglasPeuckerss = function(
   flatCoordinates, offset, endss, stride, squaredTolerance,
   simplifiedFlatCoordinates, simplifiedOffset, simplifiedEndss) {
-  let i, ii;
-  for (i = 0, ii = endss.length; i < ii; ++i) {
+  for (let i = 0, ii = endss.length; i < ii; ++i) {
     const ends = endss[i];
     const simplifiedEnds = [];
     simplifiedOffset = _ol_geom_flat_simplify_.douglasPeuckers(
@@ -356,8 +353,7 @@ _ol_geom_flat_simplify_.quantizes = function(
   flatCoordinates, offset, ends, stride,
   tolerance,
   simplifiedFlatCoordinates, simplifiedOffset, simplifiedEnds) {
-  let i, ii;
-  for (i = 0, ii = ends.length; i < ii; ++i) {
+  for (let i = 0, ii = ends.length; i < ii; ++i) {
     const end = ends[i];
     simplifiedOffset = _ol_geom_flat_simplify_.quantize(
       flatCoordinates, offset, end, stride,
@@ -386,8 +382,7 @@ _ol_geom_flat_simplify_.quantizess = function(
   flatCoordinates, offset, endss, stride,
   tolerance,
   simplifiedFlatCoordinates, simplifiedOffset, simplifiedEndss) {
-  let i, ii;
-  for (i = 0, ii = endss.length; i < ii; ++i) {
+  for (let i = 0, ii = endss.length; i < ii; ++i) {
     const ends = endss[i];
     const simplifiedEnds = [];
     simplifiedOffset = _ol_geom_flat_simplify_.quantizes(
diff --git a/src/ol/layer/Group.js b/src/ol/layer/Group.js
index 32292d0f17..5457fb3206 100644
--- a/src/ol/layer/Group.js
+++ b/src/ol/layer/Group.js
@@ -109,9 +109,8 @@ LayerGroup.prototype.handleLayersChanged_ = function(event) {
   clear(this.listenerKeys_);
 
   const layersArray = layers.getArray();
-  let i, ii, layer;
-  for (i = 0, ii = layersArray.length; i < ii; i++) {
-    layer = layersArray[i];
+  for (let i = 0, ii = layersArray.length; i < ii; i++) {
+    const layer = layersArray[i];
     this.listenerKeys_[getUid(layer).toString()] = [
       _ol_events_.listen(layer, ObjectEventType.PROPERTYCHANGE,
         this.handleLayerChange_, this),
@@ -205,9 +204,8 @@ LayerGroup.prototype.getLayerStatesArray = function(opt_states) {
   });
 
   const ownLayerState = this.getLayerState();
-  let i, ii, layerState;
-  for (i = pos, ii = states.length; i < ii; i++) {
-    layerState = states[i];
+  for (let i = pos, ii = states.length; i < ii; i++) {
+    const layerState = states[i];
     layerState.opacity *= ownLayerState.opacity;
     layerState.visible = layerState.visible && ownLayerState.visible;
     layerState.maxResolution = Math.min(
diff --git a/src/ol/layer/Heatmap.js b/src/ol/layer/Heatmap.js
index 0a4e691f39..4b1dba3dfa 100644
--- a/src/ol/layer/Heatmap.js
+++ b/src/ol/layer/Heatmap.js
@@ -243,9 +243,8 @@ Heatmap.prototype.handleRender_ = function(event) {
   const canvas = context.canvas;
   const image = context.getImageData(0, 0, canvas.width, canvas.height);
   const view8 = image.data;
-  let i, ii, alpha;
-  for (i = 0, ii = view8.length; i < ii; i += 4) {
-    alpha = view8[i + 3] * 4;
+  for (let i = 0, ii = view8.length; i < ii; i += 4) {
+    const alpha = view8[i + 3] * 4;
     if (alpha) {
       view8[i] = this.gradient_[alpha];
       view8[i + 1] = this.gradient_[alpha + 1];
diff --git a/src/ol/render/canvas/Immediate.js b/src/ol/render/canvas/Immediate.js
index af6416b908..eb47de06d0 100644
--- a/src/ol/render/canvas/Immediate.js
+++ b/src/ol/render/canvas/Immediate.js
@@ -265,8 +265,7 @@ CanvasImmediateRenderer.prototype.drawImages_ = function(flatCoordinates, offset
   if (this.imageRotateWithView_) {
     rotation += this.viewRotation_;
   }
-  let i, ii;
-  for (i = 0, ii = pixelCoordinates.length; i < ii; i += 2) {
+  for (let i = 0, ii = pixelCoordinates.length; i < ii; i += 2) {
     let x = pixelCoordinates[i] - this.imageAnchorX_;
     let y = pixelCoordinates[i + 1] - this.imageAnchorY_;
     if (this.imageSnapToPixel_) {
@@ -384,8 +383,7 @@ CanvasImmediateRenderer.prototype.moveToLineTo_ = function(flatCoordinates, offs
  * @return {number} End.
  */
 CanvasImmediateRenderer.prototype.drawRings_ = function(flatCoordinates, offset, ends, stride) {
-  let i, ii;
-  for (i = 0, ii = ends.length; i < ii; ++i) {
+  for (let i = 0, ii = ends.length; i < ii; ++i) {
     offset = this.moveToLineTo_(
       flatCoordinates, offset, ends[i], stride, true);
   }
@@ -519,8 +517,7 @@ CanvasImmediateRenderer.prototype.drawFeature = function(feature, style) {
  */
 CanvasImmediateRenderer.prototype.drawGeometryCollection = function(geometry) {
   const geometries = geometry.getGeometriesArray();
-  let i, ii;
-  for (i = 0, ii = geometries.length; i < ii; ++i) {
+  for (let i = 0, ii = geometries.length; i < ii; ++i) {
     this.drawGeometry(geometries[i]);
   }
 };
@@ -612,8 +609,7 @@ CanvasImmediateRenderer.prototype.drawMultiLineString = function(geometry) {
     const ends = geometry.getEnds();
     const stride = geometry.getStride();
     context.beginPath();
-    let i, ii;
-    for (i = 0, ii = ends.length; i < ii; ++i) {
+    for (let i = 0, ii = ends.length; i < ii; ++i) {
       offset = this.moveToLineTo_(
         flatCoordinates, offset, ends[i], stride, false);
     }
@@ -684,9 +680,8 @@ CanvasImmediateRenderer.prototype.drawMultiPolygon = function(geometry) {
     let offset = 0;
     const endss = geometry.getEndss();
     const stride = geometry.getStride();
-    let i, ii;
     context.beginPath();
-    for (i = 0, ii = endss.length; i < ii; ++i) {
+    for (let i = 0, ii = endss.length; i < ii; ++i) {
       const ends = endss[i];
       offset = this.drawRings_(flatCoordinates, offset, ends, stride);
     }
diff --git a/src/ol/render/canvas/LineStringReplay.js b/src/ol/render/canvas/LineStringReplay.js
index 3228fb443b..14193caf85 100644
--- a/src/ol/render/canvas/LineStringReplay.js
+++ b/src/ol/render/canvas/LineStringReplay.js
@@ -95,8 +95,7 @@ CanvasLineStringReplay.prototype.drawMultiLineString = function(multiLineStringG
   const flatCoordinates = multiLineStringGeometry.getFlatCoordinates();
   const stride = multiLineStringGeometry.getStride();
   let offset = 0;
-  let i, ii;
-  for (i = 0, ii = ends.length; i < ii; ++i) {
+  for (let i = 0, ii = ends.length; i < ii; ++i) {
     offset = this.drawFlatCoordinates_(
       flatCoordinates, offset, ends[i], stride);
   }
diff --git a/src/ol/render/canvas/PolygonReplay.js b/src/ol/render/canvas/PolygonReplay.js
index a034955ee7..ac0ce155c1 100644
--- a/src/ol/render/canvas/PolygonReplay.js
+++ b/src/ol/render/canvas/PolygonReplay.js
@@ -178,8 +178,7 @@ CanvasPolygonReplay.prototype.drawMultiPolygon = function(multiPolygonGeometry,
   const flatCoordinates = multiPolygonGeometry.getOrientedFlatCoordinates();
   const stride = multiPolygonGeometry.getStride();
   let offset = 0;
-  let i, ii;
-  for (i = 0, ii = endss.length; i < ii; ++i) {
+  for (let i = 0, ii = endss.length; i < ii; ++i) {
     offset = this.drawFlatCoordinatess_(
       flatCoordinates, offset, endss[i], stride);
   }
@@ -200,8 +199,7 @@ CanvasPolygonReplay.prototype.finish = function() {
   const tolerance = this.tolerance;
   if (tolerance !== 0) {
     const coordinates = this.coordinates;
-    let i, ii;
-    for (i = 0, ii = coordinates.length; i < ii; ++i) {
+    for (let i = 0, ii = coordinates.length; i < ii; ++i) {
       coordinates[i] = _ol_geom_flat_simplify_.snap(coordinates[i], tolerance);
     }
   }
diff --git a/src/ol/style/Atlas.js b/src/ol/style/Atlas.js
index d07358ce60..dc23e82929 100644
--- a/src/ol/style/Atlas.js
+++ b/src/ol/style/Atlas.js
@@ -74,9 +74,8 @@ Atlas.prototype.get = function(id) {
  * @return {?ol.AtlasInfo} The position and atlas image for the entry.
  */
 Atlas.prototype.add = function(id, width, height, renderCallback, opt_this) {
-  let block, i, ii;
-  for (i = 0, ii = this.emptyBlocks_.length; i < ii; ++i) {
-    block = this.emptyBlocks_[i];
+  for (let i = 0, ii = this.emptyBlocks_.length; i < ii; ++i) {
+    const block = this.emptyBlocks_[i];
     if (block.width >= width + this.space_ &&
         block.height >= height + this.space_) {
       // we found a block that is big enough for our entry
diff --git a/src/ol/style/AtlasManager.js b/src/ol/style/AtlasManager.js
index 7b40c260bf..8bd2b80b08 100644
--- a/src/ol/style/AtlasManager.js
+++ b/src/ol/style/AtlasManager.js
@@ -109,10 +109,9 @@ AtlasManager.prototype.getInfo = function(id) {
  *    or `null` if the entry is not part of the atlases.
  */
 AtlasManager.prototype.getInfo_ = function(atlases, id) {
-  let atlas, info, i, ii;
-  for (i = 0, ii = atlases.length; i < ii; ++i) {
-    atlas = atlases[i];
-    info = atlas.get(id);
+  for (let i = 0, ii = atlases.length; i < ii; ++i) {
+    const atlas = atlases[i];
+    const info = atlas.get(id);
     if (info) {
       return info;
     }