Use blocked scoped variables

In addition to using const and let, this also upgrades our linter config and removes lint (mostly whitespace).

examples/icon-sprite-webgl.js

@@ -8,7 +8,7 @@ import Icon from '../src/ol/style/Icon.js';
 import Style from '../src/ol/style/Style.js';
 
 
-var iconInfo = [{
+const iconInfo = [{
   offset: [0, 0],
   opacity: 1.0,
   rotateWithView: true,
@@ -38,12 +38,12 @@ var iconInfo = [{
   size: [44, 44]
 }];
 
-var i;
+let i;
 
-var iconCount = iconInfo.length;
-var icons = new Array(iconCount);
+const iconCount = iconInfo.length;
+const icons = new Array(iconCount);
 for (i = 0; i < iconCount; ++i) {
-  var info = iconInfo[i];
+  const info = iconInfo[i];
   icons[i] = new Icon({
     offset: info.offset,
     opacity: info.opacity,
@@ -56,30 +56,30 @@ for (i = 0; i < iconCount; ++i) {
   });
 }
 
-var featureCount = 50000;
-var features = new Array(featureCount);
-var feature, geometry;
-var e = 25000000;
+const featureCount = 50000;
+const features = new Array(featureCount);
+let feature, geometry;
+const e = 25000000;
 for (i = 0; i < featureCount; ++i) {
   geometry = new Point(
-      [2 * e * Math.random() - e, 2 * e * Math.random() - e]);
+    [2 * e * Math.random() - e, 2 * e * Math.random() - e]);
   feature = new Feature(geometry);
   feature.setStyle(
-      new Style({
-        image: icons[i % (iconCount - 1)]
-      })
+    new Style({
+      image: icons[i % (iconCount - 1)]
+    })
   );
   features[i] = feature;
 }
 
-var vectorSource = new VectorSource({
+const vectorSource = new VectorSource({
   features: features
 });
-var vector = new VectorLayer({
+const vector = new VectorLayer({
   source: vectorSource
 });
 
-var map = new Map({
+const map = new Map({
   renderer: /** @type {Array<ol.renderer.Type>} */ (['webgl', 'canvas']),
   layers: [vector],
   target: document.getElementById('map'),
@@ -89,9 +89,9 @@ var map = new Map({
   })
 });
 
-var overlayFeatures = [];
+const overlayFeatures = [];
 for (i = 0; i < featureCount; i += 30) {
-  var clone = features[i].clone();
+  const clone = features[i].clone();
   clone.setStyle(null);
   overlayFeatures.push(clone);
 }
@@ -107,12 +107,12 @@ new VectorLayer({
 });
 
 map.on('click', function(evt) {
-  var info = document.getElementById('info');
+  const info = document.getElementById('info');
   info.innerHTML =
       'Hold on a second, while I catch those butterflies for you ...';
 
   window.setTimeout(function() {
-    var features = [];
+    const features = [];
     map.forEachFeatureAtPixel(evt.pixel, function(feature) {
       features.push(feature);
       return false;
@@ -132,7 +132,7 @@ map.on('pointermove', function(evt) {
   if (evt.dragging) {
     return;
   }
-  var pixel = map.getEventPixel(evt.originalEvent);
-  var hit = map.hasFeatureAtPixel(pixel);
+  const pixel = map.getEventPixel(evt.originalEvent);
+  const hit = map.hasFeatureAtPixel(pixel);
   map.getTarget().style.cursor = hit ? 'pointer' : '';
 });