Remove goog.isNull in layer classes

src/ol/layer/heatmaplayer.js

@@ -106,8 +106,7 @@ ol.layer.Heatmap = function(opt_options) {
       'weightFunction should be a function');
 
   this.setStyle(goog.bind(function(feature, resolution) {
-    goog.asserts.assert(!goog.isNull(this.styleCache_),
-        'this.styleCache_ should not be null');
+    goog.asserts.assert(this.styleCache_, 'this.styleCache_ expected');
     goog.asserts.assert(this.circleImage_ !== undefined,
         'this.circleImage_ should be defined');
     var weight = weightFunction(feature);
@@ -252,8 +251,7 @@ ol.layer.Heatmap.prototype.handleStyleChanged_ = function() {
 ol.layer.Heatmap.prototype.handleRender_ = function(event) {
   goog.asserts.assert(event.type == ol.render.EventType.RENDER,
       'event.type should be RENDER');
-  goog.asserts.assert(!goog.isNull(this.gradient_),
-      'this.gradient_ should not be null');
+  goog.asserts.assert(this.gradient_, 'this.gradient_ expected');
   var context = event.context;
   var canvas = context.canvas;
   var image = context.getImageData(0, 0, canvas.width, canvas.height);

src/ol/layer/layer.js

@@ -118,7 +118,7 @@ ol.layer.Layer.prototype.getSource = function() {
   */
 ol.layer.Layer.prototype.getSourceState = function() {
   var source = this.getSource();
-  return goog.isNull(source) ? ol.source.State.UNDEFINED : source.getState();
+  return !source ? ol.source.State.UNDEFINED : source.getState();
 };
 
 
@@ -134,12 +134,12 @@ ol.layer.Layer.prototype.handleSourceChange_ = function() {
  * @private
  */
 ol.layer.Layer.prototype.handleSourcePropertyChange_ = function() {
-  if (!goog.isNull(this.sourceChangeKey_)) {
+  if (this.sourceChangeKey_) {
     goog.events.unlistenByKey(this.sourceChangeKey_);
     this.sourceChangeKey_ = null;
   }
   var source = this.getSource();
-  if (!goog.isNull(source)) {
+  if (source) {
     this.sourceChangeKey_ = goog.events.listen(source,
         goog.events.EventType.CHANGE, this.handleSourceChange_, false, this);
   }
@@ -162,12 +162,12 @@ ol.layer.Layer.prototype.handleSourcePropertyChange_ = function() {
 ol.layer.Layer.prototype.setMap = function(map) {
   goog.events.unlistenByKey(this.mapPrecomposeKey_);
   this.mapPrecomposeKey_ = null;
-  if (goog.isNull(map)) {
+  if (!map) {
     this.changed();
   }
   goog.events.unlistenByKey(this.mapRenderKey_);
   this.mapRenderKey_ = null;
-  if (!goog.isNull(map)) {
+  if (map) {
     this.mapPrecomposeKey_ = goog.events.listen(
         map, ol.render.EventType.PRECOMPOSE, function(evt) {
           var layerState = this.getLayerState();

src/ol/layer/vectorlayer.js

@@ -35,7 +35,7 @@ ol.layer.Vector = function(opt_options) {
       opt_options : /** @type {olx.layer.VectorOptions} */ ({});
 
   goog.asserts.assert(
-      options.renderOrder === undefined || goog.isNull(options.renderOrder) ||
+      options.renderOrder === undefined || !options.renderOrder ||
       goog.isFunction(options.renderOrder),
       'renderOrder must be a comparator function');
 
@@ -161,7 +161,7 @@ ol.layer.Vector.prototype.getUpdateWhileInteracting = function() {
  */
 ol.layer.Vector.prototype.setRenderOrder = function(renderOrder) {
   goog.asserts.assert(
-      renderOrder === undefined || goog.isNull(renderOrder) ||
+      renderOrder === undefined || !renderOrder ||
       goog.isFunction(renderOrder),
       'renderOrder must be a comparator function');
   this.set(ol.layer.VectorProperty.RENDER_ORDER, renderOrder);
@@ -181,7 +181,7 @@ ol.layer.Vector.prototype.setRenderOrder = function(renderOrder) {
  */
 ol.layer.Vector.prototype.setStyle = function(style) {
   this.style_ = style !== undefined ? style : ol.style.defaultStyleFunction;
-  this.styleFunction_ = goog.isNull(style) ?
+  this.styleFunction_ = style === null ?
       undefined : ol.style.createStyleFunction(this.style_);
   this.changed();
 };