Reset opacity when setOpacity is called without args

src/ui/marker.test.ts

@@ -867,6 +867,16 @@ describe('marker', () => {
         map.remove();
     });
 
+    test('Resets opacity to default when setOpacity is called without arguments', () => {
+        const map = createMap();
+        const marker = new Marker({opacity: 0.7})
+            .setLngLat([0, 0])
+            .addTo(map);
+        marker.setOpacity();
+        expect(marker.getElement().style.opacity).toBe('1');
+        map.remove();
+    });
+
     test('Marker changes opacity behind terrain and when terrain is removed', () => {
         const map = createMap();
         map.transform.lngLatToCameraDepth = () => .95; // Mocking distance to marker

src/ui/marker.ts

@@ -814,11 +814,16 @@ export class Marker extends Evented {
     }
 
     /**
-     * Sets the `opacity` property of the marker.
+     * Sets the `opacity` and `opacityWhenCovered` properties of the marker.
      * @param opacity - Sets the `opacity` property of the marker.
+     * @param opacityWhenCovered - Sets the `opacityWhenCovered` property of the marker.
      * @returns `this`
      */
     setOpacity(opacity?: number, opacityWhenCovered?: number): this {
+        if (opacity === undefined && opacityWhenCovered === undefined) {
+            this._opacity = 1;
+            this._opacityWhenCovered = 0.2;
+        }
         if (opacity !== undefined) {
             this._opacity = opacity;
         }