Add hasFeature method to ol.source.Vector

src/ol/source/Vector.js

@@ -827,6 +827,21 @@ VectorSource.prototype.handleFeatureChange_ = function(event) {
     VectorEventType.CHANGEFEATURE, feature));
 };
 
+/**
+ * Returns true if the feature is contained within the source.
+ * @param {ol.Feature} feature Feature.
+ * @return {boolean} Has feature.
+ * @api
+ */
+VectorSource.prototype.hasFeature = function(feature) {
+  const id = feature.getId();
+  if (id !== undefined) {
+    return id in this.idIndex_;
+  } else {
+    const featureKey = getUid(feature).toString();
+    return featureKey in this.undefIdIndex_;
+  }
+};
 
 /**
  * @return {boolean} Is empty.

test/spec/ol/source/vector.test.js

@@ -85,6 +85,35 @@ describe('ol.source.Vector', function() {
 
     });
 
+    describe('#hasFeature', function() {
+
+      it('returns true for added feature without id', function() {
+        const feature = new Feature();
+        vectorSource.addFeature(feature);
+        expect(vectorSource.hasFeature(feature)).to.be(true);
+      });
+
+      it('returns true for added feature with id', function() {
+        const feature = new Feature();
+        feature.setId('1');
+        vectorSource.addFeature(feature);
+        expect(vectorSource.hasFeature(feature)).to.be(true);
+      });
+
+      it('return false for removed feature', function() {
+        const feature = new Feature();
+        vectorSource.addFeature(feature);
+        vectorSource.removeFeature(feature);
+        expect(vectorSource.hasFeature(feature)).to.be(false);
+      });
+
+      it('returns false for non-added feature', function() {
+        const feature = new Feature();
+        expect(vectorSource.hasFeature(feature)).to.be(false);
+      });
+
+    });
+
   });
 
   describe('when populated with 3 features', function() {