Merge pull request #9983 from KlausBenndorf/get-features-returns-array

getFeaturesAtPixel always returns array

changelog/upgrade-notes.md

@@ -279,6 +279,10 @@ The `getGetFeatureInfoUrl` of `ol/source/ImageWMS` and `ol/source/TileWMS` is no
 
 The `SelectInteraction` is removed. There are two examples ([Select Features by Hover](https://openlayers.org/en/master/examples/select-hover-features.html) and [Select multiple Features](https://openlayers.org/en/master/examples/select-multiple-features.html) which show how similar results can be achieved by using more basic methods.
 
+##### `getFeatureAtPixel` returns always an array
+
+`getFeatureAtPixel` returns now an empty array instead of `null` if no features were found. 
+
 #### Other changes
 
 ##### Allow declutter in image render mode

src/ol/PluggableMap.js

@@ -562,15 +562,12 @@ class PluggableMap extends BaseObject {
    * @param {import("./pixel.js").Pixel} pixel Pixel.
    * @param {AtPixelOptions=} opt_options Optional options.
    * @return {Array<import("./Feature.js").FeatureLike>} The detected features or
-   * `null` if none were found.
+   * an empty array if none were found.
    * @api
    */
   getFeaturesAtPixel(pixel, opt_options) {
-    let features = null;
+    const features = [];
     this.forEachFeatureAtPixel(pixel, function(feature) {
-      if (!features) {
-        features = [];
-      }
       features.push(feature);
     }, opt_options);
     return features;

test/spec/ol/map.test.js

@@ -279,9 +279,10 @@ describe('ol.Map', function() {
       document.body.removeChild(target);
     });
 
-    it('returns null if no feature was found', function() {
+    it('returns an empty array if no feature was found', function() {
       const features = map.getFeaturesAtPixel([0, 0]);
-      expect(features).to.be(null);
+      expect(features).to.be.an(Array);
+      expect(features).to.be.empty();
     });
 
     it('returns an array of found features', function() {
@@ -311,10 +312,11 @@ describe('ol.Map', function() {
       map.addLayer(otherLayer);
       const features = map.getFeaturesAtPixel([50, 50], {
         layerFilter: function(layer) {
-          return layer == otherLayer;
+          return layer === otherLayer;
         }
       });
-      expect(features).to.be(null);
+      expect(features).to.be.an(Array);
+      expect(features).to.be.empty();
     });
 
   });

test/spec/ol/renderer/canvas/vectortilelayer.test.js

@@ -369,7 +369,8 @@ describe('ol.renderer.canvas.VectorTileLayer', function() {
           const features = map.getFeaturesAtPixel([96, 96]);
           document.body.removeChild(target);
           map.dispose();
-          expect(features).to.be(null);
+          expect(features).to.be.an(Array);
+          expect(features).to.be.empty();
           done();
         }, 200);
       });