diff --git a/src/ol/pointer/EventSource.js b/src/ol/pointer/EventSource.js
index 46547520d3..6f3971506b 100644
--- a/src/ol/pointer/EventSource.js
+++ b/src/ol/pointer/EventSource.js
@@ -1,42 +1,45 @@
 /**
  * @module ol/pointer/EventSource
  */
-/**
- * @param {module:ol/pointer/PointerEventHandler} dispatcher Event handler.
- * @param {!Object.<string, function(Event)>} mapping Event mapping.
- * @constructor
- */
+
 class EventSource {
+
+  /**
+   * @param {module:ol/pointer/PointerEventHandler} dispatcher Event handler.
+   * @param {!Object.<string, function(Event)>} mapping Event mapping.
+   */
   constructor(dispatcher, mapping) {
+
     /**
-    * @type {module:ol/pointer/PointerEventHandler}
-    */
+     * @type {module:ol/pointer/PointerEventHandler}
+     */
     this.dispatcher = dispatcher;
 
     /**
-    * @private
-    * @const
-    * @type {!Object.<string, function(Event)>}
-    */
+     * @private
+     * @const
+     * @type {!Object.<string, function(Event)>}
+     */
     this.mapping_ = mapping;
   }
 
   /**
-  * List of events supported by this source.
-  * @return {Array.<string>} Event names
-  */
+   * List of events supported by this source.
+   * @return {Array.<string>} Event names
+   */
   getEvents() {
     return Object.keys(this.mapping_);
   }
 
   /**
-  * Returns the handler that should handle a given event type.
-  * @param {string} eventType The event type.
-  * @return {function(Event)} Handler
-  */
+   * Returns the handler that should handle a given event type.
+   * @param {string} eventType The event type.
+   * @return {function(Event)} Handler
+   */
   getHandlerForEvent(eventType) {
     return this.mapping_[eventType];
   }
+
 }
 
 export default EventSource;
diff --git a/src/ol/pointer/MouseSource.js b/src/ol/pointer/MouseSource.js
index 1c8c69e345..90b2f27ef7 100644
--- a/src/ol/pointer/MouseSource.js
+++ b/src/ol/pointer/MouseSource.js
@@ -1,6 +1,7 @@
 /**
  * @module ol/pointer/MouseSource
  */
+
 // Based on https://github.com/Polymer/PointerEvents
 
 // Copyright (c) 2013 The Polymer Authors. All rights reserved.
@@ -31,7 +32,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-import {inherits} from '../util.js';
 import EventSource from '../pointer/EventSource.js';
 
 
@@ -54,22 +54,97 @@ export const POINTER_TYPE = 'mouse';
  */
 const DEDUP_DIST = 25;
 
+/**
+ * Handler for `mousedown`.
+ *
+ * @this {module:ol/pointer/MouseSource}
+ * @param {MouseEvent} inEvent The in event.
+ */
+function mousedown(inEvent) {
+  if (!this.isEventSimulatedFromTouch_(inEvent)) {
+    // TODO(dfreedman) workaround for some elements not sending mouseup
+    // http://crbug/149091
+    if (POINTER_ID.toString() in this.pointerMap) {
+      this.cancel(inEvent);
+    }
+    const e = prepareEvent(inEvent, this.dispatcher);
+    this.pointerMap[POINTER_ID.toString()] = inEvent;
+    this.dispatcher.down(e, inEvent);
+  }
+}
 
 /**
- * @param {module:ol/pointer/PointerEventHandler} dispatcher Event handler.
- * @constructor
- * @extends {module:ol/pointer/EventSource}
+ * Handler for `mousemove`.
+ *
+ * @this {module:ol/pointer/MouseSource}
+ * @param {MouseEvent} inEvent The in event.
  */
-class MouseSource {
+function mousemove(inEvent) {
+  if (!this.isEventSimulatedFromTouch_(inEvent)) {
+    const e = prepareEvent(inEvent, this.dispatcher);
+    this.dispatcher.move(e, inEvent);
+  }
+}
+
+/**
+ * Handler for `mouseup`.
+ *
+ * @this {module:ol/pointer/MouseSource}
+ * @param {MouseEvent} inEvent The in event.
+ */
+function mouseup(inEvent) {
+  if (!this.isEventSimulatedFromTouch_(inEvent)) {
+    const p = this.pointerMap[POINTER_ID.toString()];
+
+    if (p && p.button === inEvent.button) {
+      const e = prepareEvent(inEvent, this.dispatcher);
+      this.dispatcher.up(e, inEvent);
+      this.cleanupMouse();
+    }
+  }
+}
+
+/**
+ * Handler for `mouseover`.
+ *
+ * @this {module:ol/pointer/MouseSource}
+ * @param {MouseEvent} inEvent The in event.
+ */
+function mouseover(inEvent) {
+  if (!this.isEventSimulatedFromTouch_(inEvent)) {
+    const e = prepareEvent(inEvent, this.dispatcher);
+    this.dispatcher.enterOver(e, inEvent);
+  }
+}
+
+/**
+ * Handler for `mouseout`.
+ *
+ * @this {module:ol/pointer/MouseSource}
+ * @param {MouseEvent} inEvent The in event.
+ */
+function mouseout(inEvent) {
+  if (!this.isEventSimulatedFromTouch_(inEvent)) {
+    const e = prepareEvent(inEvent, this.dispatcher);
+    this.dispatcher.leaveOut(e, inEvent);
+  }
+}
+
+
+class MouseSource extends EventSource {
+
+  /**
+   * @param {module:ol/pointer/PointerEventHandler} dispatcher Event handler.
+   */
   constructor(dispatcher) {
     const mapping = {
-      'mousedown': this.mousedown,
-      'mousemove': this.mousemove,
-      'mouseup': this.mouseup,
-      'mouseover': this.mouseover,
-      'mouseout': this.mouseout
+      'mousedown': mousedown,
+      'mousemove': mousemove,
+      'mouseup': mouseup,
+      'mouseover': mouseover,
+      'mouseout': mouseout
     };
-    EventSource.call(this, dispatcher, mapping);
+    super(dispatcher, mapping);
 
     /**
      * @const
@@ -123,77 +198,6 @@ class MouseSource {
     return false;
   }
 
-  /**
-   * Handler for `mousedown`.
-   *
-   * @param {MouseEvent} inEvent The in event.
-   */
-  mousedown(inEvent) {
-    if (!this.isEventSimulatedFromTouch_(inEvent)) {
-      // TODO(dfreedman) workaround for some elements not sending mouseup
-      // http://crbug/149091
-      if (POINTER_ID.toString() in this.pointerMap) {
-        this.cancel(inEvent);
-      }
-      const e = prepareEvent(inEvent, this.dispatcher);
-      this.pointerMap[POINTER_ID.toString()] = inEvent;
-      this.dispatcher.down(e, inEvent);
-    }
-  }
-
-  /**
-   * Handler for `mousemove`.
-   *
-   * @param {MouseEvent} inEvent The in event.
-   */
-  mousemove(inEvent) {
-    if (!this.isEventSimulatedFromTouch_(inEvent)) {
-      const e = prepareEvent(inEvent, this.dispatcher);
-      this.dispatcher.move(e, inEvent);
-    }
-  }
-
-  /**
-   * Handler for `mouseup`.
-   *
-   * @param {MouseEvent} inEvent The in event.
-   */
-  mouseup(inEvent) {
-    if (!this.isEventSimulatedFromTouch_(inEvent)) {
-      const p = this.pointerMap[POINTER_ID.toString()];
-
-      if (p && p.button === inEvent.button) {
-        const e = prepareEvent(inEvent, this.dispatcher);
-        this.dispatcher.up(e, inEvent);
-        this.cleanupMouse();
-      }
-    }
-  }
-
-  /**
-   * Handler for `mouseover`.
-   *
-   * @param {MouseEvent} inEvent The in event.
-   */
-  mouseover(inEvent) {
-    if (!this.isEventSimulatedFromTouch_(inEvent)) {
-      const e = prepareEvent(inEvent, this.dispatcher);
-      this.dispatcher.enterOver(e, inEvent);
-    }
-  }
-
-  /**
-   * Handler for `mouseout`.
-   *
-   * @param {MouseEvent} inEvent The in event.
-   */
-  mouseout(inEvent) {
-    if (!this.isEventSimulatedFromTouch_(inEvent)) {
-      const e = prepareEvent(inEvent, this.dispatcher);
-      this.dispatcher.leaveOut(e, inEvent);
-    }
-  }
-
   /**
    * Dispatches a `pointercancel` event.
    *
@@ -213,8 +217,6 @@ class MouseSource {
   }
 }
 
-inherits(MouseSource, EventSource);
-
 
 /**
  * Creates a copy of the original event that will be used
diff --git a/src/ol/pointer/MsSource.js b/src/ol/pointer/MsSource.js
index 230b0aba9d..17e174c0c6 100644
--- a/src/ol/pointer/MsSource.js
+++ b/src/ol/pointer/MsSource.js
@@ -31,7 +31,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-import {inherits} from '../util.js';
 import EventSource from '../pointer/EventSource.js';
 
 
@@ -47,41 +46,130 @@ const POINTER_TYPES = [
   'mouse'
 ];
 
+/**
+ * Handler for `msPointerDown`.
+ *
+ * @this {module:ol/pointer/MsSource}
+ * @param {MSPointerEvent} inEvent The in event.
+ */
+function msPointerDown(inEvent) {
+  this.pointerMap[inEvent.pointerId.toString()] = inEvent;
+  const e = this.prepareEvent_(inEvent);
+  this.dispatcher.down(e, inEvent);
+}
 
 /**
- * @param {module:ol/pointer/PointerEventHandler} dispatcher Event handler.
- * @constructor
- * @extends {module:ol/pointer/EventSource}
+ * Handler for `msPointerMove`.
+ *
+ * @this {module:ol/pointer/MsSource}
+ * @param {MSPointerEvent} inEvent The in event.
  */
-class MsSource {
+function msPointerMove(inEvent) {
+  const e = this.prepareEvent_(inEvent);
+  this.dispatcher.move(e, inEvent);
+}
+
+/**
+ * Handler for `msPointerUp`.
+ *
+ * @this {module:ol/pointer/MsSource}
+ * @param {MSPointerEvent} inEvent The in event.
+ */
+function msPointerUp(inEvent) {
+  const e = this.prepareEvent_(inEvent);
+  this.dispatcher.up(e, inEvent);
+  this.cleanup(inEvent.pointerId);
+}
+
+/**
+ * Handler for `msPointerOut`.
+ *
+ * @this {module:ol/pointer/MsSource}
+ * @param {MSPointerEvent} inEvent The in event.
+ */
+function msPointerOut(inEvent) {
+  const e = this.prepareEvent_(inEvent);
+  this.dispatcher.leaveOut(e, inEvent);
+}
+
+/**
+ * Handler for `msPointerOver`.
+ *
+ * @this {module:ol/pointer/MsSource}
+ * @param {MSPointerEvent} inEvent The in event.
+ */
+function msPointerOver(inEvent) {
+  const e = this.prepareEvent_(inEvent);
+  this.dispatcher.enterOver(e, inEvent);
+}
+
+/**
+ * Handler for `msPointerCancel`.
+ *
+ * @this {module:ol/pointer/MsSource}
+ * @param {MSPointerEvent} inEvent The in event.
+ */
+function msPointerCancel(inEvent) {
+  const e = this.prepareEvent_(inEvent);
+  this.dispatcher.cancel(e, inEvent);
+  this.cleanup(inEvent.pointerId);
+}
+
+/**
+ * Handler for `msLostPointerCapture`.
+ *
+ * @this {module:ol/pointer/MsSource}
+ * @param {MSPointerEvent} inEvent The in event.
+ */
+function msLostPointerCapture(inEvent) {
+  const e = this.dispatcher.makeEvent('lostpointercapture', inEvent, inEvent);
+  this.dispatcher.dispatchEvent(e);
+}
+
+/**
+ * Handler for `msGotPointerCapture`.
+ *
+ * @this {module:ol/pointer/MsSource}
+ * @param {MSPointerEvent} inEvent The in event.
+ */
+function msGotPointerCapture(inEvent) {
+  const e = this.dispatcher.makeEvent('gotpointercapture', inEvent, inEvent);
+  this.dispatcher.dispatchEvent(e);
+}
+
+class MsSource extends EventSource {
+
+  /**
+   * @param {module:ol/pointer/PointerEventHandler} dispatcher Event handler.
+   */
   constructor(dispatcher) {
     const mapping = {
-      'MSPointerDown': this.msPointerDown,
-      'MSPointerMove': this.msPointerMove,
-      'MSPointerUp': this.msPointerUp,
-      'MSPointerOut': this.msPointerOut,
-      'MSPointerOver': this.msPointerOver,
-      'MSPointerCancel': this.msPointerCancel,
-      'MSGotPointerCapture': this.msGotPointerCapture,
-      'MSLostPointerCapture': this.msLostPointerCapture
+      'MSPointerDown': msPointerDown,
+      'MSPointerMove': msPointerMove,
+      'MSPointerUp': msPointerUp,
+      'MSPointerOut': msPointerOut,
+      'MSPointerOver': msPointerOver,
+      'MSPointerCancel': msPointerCancel,
+      'MSGotPointerCapture': msGotPointerCapture,
+      'MSLostPointerCapture': msLostPointerCapture
     };
-    EventSource.call(this, dispatcher, mapping);
+    super(dispatcher, mapping);
 
     /**
-    * @const
-    * @type {!Object.<string, MSPointerEvent|Object>}
-    */
+     * @const
+     * @type {!Object.<string, MSPointerEvent|Object>}
+     */
     this.pointerMap = dispatcher.pointerMap;
   }
 
   /**
-  * Creates a copy of the original event that will be used
-  * for the fake pointer event.
-  *
-  * @private
-  * @param {MSPointerEvent} inEvent The in event.
-  * @return {Object} The copied event.
-  */
+   * Creates a copy of the original event that will be used
+   * for the fake pointer event.
+   *
+   * @private
+   * @param {MSPointerEvent} inEvent The in event.
+   * @return {Object} The copied event.
+   */
   prepareEvent_(inEvent) {
     let e = inEvent;
     if (typeof inEvent.pointerType === 'number') {
@@ -93,97 +181,13 @@ class MsSource {
   }
 
   /**
-  * Remove this pointer from the list of active pointers.
-  * @param {number} pointerId Pointer identifier.
-  */
+   * Remove this pointer from the list of active pointers.
+   * @param {number} pointerId Pointer identifier.
+   */
   cleanup(pointerId) {
     delete this.pointerMap[pointerId.toString()];
   }
 
-  /**
-  * Handler for `msPointerDown`.
-  *
-  * @param {MSPointerEvent} inEvent The in event.
-  */
-  msPointerDown(inEvent) {
-    this.pointerMap[inEvent.pointerId.toString()] = inEvent;
-    const e = this.prepareEvent_(inEvent);
-    this.dispatcher.down(e, inEvent);
-  }
-
-  /**
-  * Handler for `msPointerMove`.
-  *
-  * @param {MSPointerEvent} inEvent The in event.
-  */
-  msPointerMove(inEvent) {
-    const e = this.prepareEvent_(inEvent);
-    this.dispatcher.move(e, inEvent);
-  }
-
-  /**
-  * Handler for `msPointerUp`.
-  *
-  * @param {MSPointerEvent} inEvent The in event.
-  */
-  msPointerUp(inEvent) {
-    const e = this.prepareEvent_(inEvent);
-    this.dispatcher.up(e, inEvent);
-    this.cleanup(inEvent.pointerId);
-  }
-
-  /**
-  * Handler for `msPointerOut`.
-  *
-  * @param {MSPointerEvent} inEvent The in event.
-  */
-  msPointerOut(inEvent) {
-    const e = this.prepareEvent_(inEvent);
-    this.dispatcher.leaveOut(e, inEvent);
-  }
-
-  /**
-  * Handler for `msPointerOver`.
-  *
-  * @param {MSPointerEvent} inEvent The in event.
-  */
-  msPointerOver(inEvent) {
-    const e = this.prepareEvent_(inEvent);
-    this.dispatcher.enterOver(e, inEvent);
-  }
-
-  /**
-  * Handler for `msPointerCancel`.
-  *
-  * @param {MSPointerEvent} inEvent The in event.
-  */
-  msPointerCancel(inEvent) {
-    const e = this.prepareEvent_(inEvent);
-    this.dispatcher.cancel(e, inEvent);
-    this.cleanup(inEvent.pointerId);
-  }
-
-  /**
-  * Handler for `msLostPointerCapture`.
-  *
-  * @param {MSPointerEvent} inEvent The in event.
-  */
-  msLostPointerCapture(inEvent) {
-    const e = this.dispatcher.makeEvent('lostpointercapture', inEvent, inEvent);
-    this.dispatcher.dispatchEvent(e);
-  }
-
-  /**
-  * Handler for `msGotPointerCapture`.
-  *
-  * @param {MSPointerEvent} inEvent The in event.
-  */
-  msGotPointerCapture(inEvent) {
-    const e = this.dispatcher.makeEvent('gotpointercapture', inEvent, inEvent);
-    this.dispatcher.dispatchEvent(e);
-  }
 }
 
-inherits(MsSource, EventSource);
-
 export default MsSource;
diff --git a/src/ol/pointer/NativeSource.js b/src/ol/pointer/NativeSource.js
index 0ac60c42bd..34986ecbec 100644
--- a/src/ol/pointer/NativeSource.js
+++ b/src/ol/pointer/NativeSource.js
@@ -1,6 +1,7 @@
 /**
  * @module ol/pointer/NativeSource
  */
+
 // Based on https://github.com/Polymer/PointerEvents
 
 // Copyright (c) 2013 The Polymer Authors. All rights reserved.
@@ -31,103 +32,107 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-import {inherits} from '../util.js';
 import EventSource from '../pointer/EventSource.js';
 
 /**
- * @param {module:ol/pointer/PointerEventHandler} dispatcher Event handler.
- * @constructor
- * @extends {module:ol/pointer/EventSource}
+ * Handler for `pointerdown`.
+ *
+ * @this {module:ol/pointer/NativeSource}
+ * @param {Event} inEvent The in event.
  */
-class NativeSource {
-  constructor(dispatcher) {
-    const mapping = {
-      'pointerdown': this.pointerDown,
-      'pointermove': this.pointerMove,
-      'pointerup': this.pointerUp,
-      'pointerout': this.pointerOut,
-      'pointerover': this.pointerOver,
-      'pointercancel': this.pointerCancel,
-      'gotpointercapture': this.gotPointerCapture,
-      'lostpointercapture': this.lostPointerCapture
-    };
-    EventSource.call(this, dispatcher, mapping);
-  }
-
-  /**
-  * Handler for `pointerdown`.
-  *
-  * @param {Event} inEvent The in event.
-  */
-  pointerDown(inEvent) {
-    this.dispatcher.fireNativeEvent(inEvent);
-  }
-
-  /**
-  * Handler for `pointermove`.
-  *
-  * @param {Event} inEvent The in event.
-  */
-  pointerMove(inEvent) {
-    this.dispatcher.fireNativeEvent(inEvent);
-  }
-
-  /**
-  * Handler for `pointerup`.
-  *
-  * @param {Event} inEvent The in event.
-  */
-  pointerUp(inEvent) {
-    this.dispatcher.fireNativeEvent(inEvent);
-  }
-
-  /**
-  * Handler for `pointerout`.
-  *
-  * @param {Event} inEvent The in event.
-  */
-  pointerOut(inEvent) {
-    this.dispatcher.fireNativeEvent(inEvent);
-  }
-
-  /**
-  * Handler for `pointerover`.
-  *
-  * @param {Event} inEvent The in event.
-  */
-  pointerOver(inEvent) {
-    this.dispatcher.fireNativeEvent(inEvent);
-  }
-
-  /**
-  * Handler for `pointercancel`.
-  *
-  * @param {Event} inEvent The in event.
-  */
-  pointerCancel(inEvent) {
-    this.dispatcher.fireNativeEvent(inEvent);
-  }
-
-  /**
-  * Handler for `lostpointercapture`.
-  *
-  * @param {Event} inEvent The in event.
-  */
-  lostPointerCapture(inEvent) {
-    this.dispatcher.fireNativeEvent(inEvent);
-  }
-
-  /**
-  * Handler for `gotpointercapture`.
-  *
-  * @param {Event} inEvent The in event.
-  */
-  gotPointerCapture(inEvent) {
-    this.dispatcher.fireNativeEvent(inEvent);
-  }
+function pointerDown(inEvent) {
+  this.dispatcher.fireNativeEvent(inEvent);
 }
 
-inherits(NativeSource, EventSource);
+/**
+ * Handler for `pointermove`.
+ *
+ * @this {module:ol/pointer/NativeSource}
+ * @param {Event} inEvent The in event.
+ */
+function pointerMove(inEvent) {
+  this.dispatcher.fireNativeEvent(inEvent);
+}
 
+/**
+ * Handler for `pointerup`.
+ *
+ * @this {module:ol/pointer/NativeSource}
+ * @param {Event} inEvent The in event.
+ */
+function pointerUp(inEvent) {
+  this.dispatcher.fireNativeEvent(inEvent);
+}
+
+/**
+ * Handler for `pointerout`.
+ *
+ * @this {module:ol/pointer/NativeSource}
+ * @param {Event} inEvent The in event.
+ */
+function pointerOut(inEvent) {
+  this.dispatcher.fireNativeEvent(inEvent);
+}
+
+/**
+ * Handler for `pointerover`.
+ *
+ * @this {module:ol/pointer/NativeSource}
+ * @param {Event} inEvent The in event.
+ */
+function pointerOver(inEvent) {
+  this.dispatcher.fireNativeEvent(inEvent);
+}
+
+/**
+ * Handler for `pointercancel`.
+ *
+ * @this {module:ol/pointer/NativeSource}
+ * @param {Event} inEvent The in event.
+ */
+function pointerCancel(inEvent) {
+  this.dispatcher.fireNativeEvent(inEvent);
+}
+
+/**
+ * Handler for `lostpointercapture`.
+ *
+ * @this {module:ol/pointer/NativeSource}
+ * @param {Event} inEvent The in event.
+ */
+function lostPointerCapture(inEvent) {
+  this.dispatcher.fireNativeEvent(inEvent);
+}
+
+/**
+ * Handler for `gotpointercapture`.
+ *
+ * @this {module:ol/pointer/NativeSource}
+ * @param {Event} inEvent The in event.
+ */
+function gotPointerCapture(inEvent) {
+  this.dispatcher.fireNativeEvent(inEvent);
+}
+
+class NativeSource extends EventSource {
+
+  /**
+   * @param {module:ol/pointer/PointerEventHandler} dispatcher Event handler.
+   */
+  constructor(dispatcher) {
+    const mapping = {
+      'pointerdown': pointerDown,
+      'pointermove': pointerMove,
+      'pointerup': pointerUp,
+      'pointerout': pointerOut,
+      'pointerover': pointerOver,
+      'pointercancel': pointerCancel,
+      'gotpointercapture': gotPointerCapture,
+      'lostpointercapture': lostPointerCapture
+    };
+    super(dispatcher, mapping);
+  }
+
+}
 
 export default NativeSource;
diff --git a/src/ol/pointer/PointerEvent.js b/src/ol/pointer/PointerEvent.js
index f21ad0aa11..acaffe16c7 100644
--- a/src/ol/pointer/PointerEvent.js
+++ b/src/ol/pointer/PointerEvent.js
@@ -1,6 +1,7 @@
 /**
  * @module ol/pointer/PointerEvent
  */
+
 // Based on https://github.com/Polymer/PointerEvents
 
 // Copyright (c) 2013 The Polymer Authors. All rights reserved.
@@ -31,7 +32,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-import {inherits} from '../util.js';
 import Event from '../events/Event.js';
 
 
@@ -42,155 +42,154 @@ import Event from '../events/Event.js';
 let HAS_BUTTONS = false;
 
 
-/**
- * A class for pointer events.
- *
- * This class is used as an abstraction for mouse events,
- * touch events and even native pointer events.
- *
- * @constructor
- * @extends {module:ol/events/Event}
- * @param {string} type The type of the event to create.
- * @param {Event} originalEvent The event.
- * @param {Object.<string, ?>=} opt_eventDict An optional dictionary of
- *    initial event properties.
- */
-class PointerEvent {
+class PointerEvent extends Event {
+
+  /**
+   * A class for pointer events.
+   *
+   * This class is used as an abstraction for mouse events,
+   * touch events and even native pointer events.
+   *
+   * @param {string} type The type of the event to create.
+   * @param {Event} originalEvent The event.
+   * @param {Object.<string, ?>=} opt_eventDict An optional dictionary of
+   *    initial event properties.
+   */
   constructor(type, originalEvent, opt_eventDict) {
-    Event.call(this, type);
+    super(type);
 
     /**
-    * @const
-    * @type {Event}
-    */
+     * @const
+     * @type {Event}
+     */
     this.originalEvent = originalEvent;
 
     const eventDict = opt_eventDict ? opt_eventDict : {};
 
     /**
-    * @type {number}
-    */
+     * @type {number}
+     */
     this.buttons = this.getButtons_(eventDict);
 
     /**
-    * @type {number}
-    */
+     * @type {number}
+     */
     this.pressure = this.getPressure_(eventDict, this.buttons);
 
     // MouseEvent related properties
 
     /**
-    * @type {boolean}
-    */
+     * @type {boolean}
+     */
     this.bubbles = 'bubbles' in eventDict ? eventDict['bubbles'] : false;
 
     /**
-    * @type {boolean}
-    */
+     * @type {boolean}
+     */
     this.cancelable = 'cancelable' in eventDict ? eventDict['cancelable'] : false;
 
     /**
-    * @type {Object}
-    */
+     * @type {Object}
+     */
     this.view = 'view' in eventDict ? eventDict['view'] : null;
 
     /**
-    * @type {number}
-    */
+     * @type {number}
+     */
     this.detail = 'detail' in eventDict ? eventDict['detail'] : null;
 
     /**
-    * @type {number}
-    */
+     * @type {number}
+     */
     this.screenX = 'screenX' in eventDict ? eventDict['screenX'] : 0;
 
     /**
-    * @type {number}
-    */
+     * @type {number}
+     */
     this.screenY = 'screenY' in eventDict ? eventDict['screenY'] : 0;
 
     /**
-    * @type {number}
-    */
+     * @type {number}
+     */
     this.clientX = 'clientX' in eventDict ? eventDict['clientX'] : 0;
 
     /**
-    * @type {number}
-    */
+     * @type {number}
+     */
     this.clientY = 'clientY' in eventDict ? eventDict['clientY'] : 0;
 
     /**
-    * @type {boolean}
-    */
+     * @type {boolean}
+     */
     this.ctrlKey = 'ctrlKey' in eventDict ? eventDict['ctrlKey'] : false;
 
     /**
-    * @type {boolean}
-    */
+     * @type {boolean}
+     */
     this.altKey = 'altKey' in eventDict ? eventDict['altKey'] : false;
 
     /**
-    * @type {boolean}
-    */
+     * @type {boolean}
+     */
     this.shiftKey = 'shiftKey' in eventDict ? eventDict['shiftKey'] : false;
 
     /**
-    * @type {boolean}
-    */
+     * @type {boolean}
+     */
     this.metaKey = 'metaKey' in eventDict ? eventDict['metaKey'] : false;
 
     /**
-    * @type {number}
-    */
+     * @type {number}
+     */
     this.button = 'button' in eventDict ? eventDict['button'] : 0;
 
     /**
-    * @type {Node}
-    */
+     * @type {Node}
+     */
     this.relatedTarget = 'relatedTarget' in eventDict ?
       eventDict['relatedTarget'] : null;
 
     // PointerEvent related properties
 
     /**
-    * @const
-    * @type {number}
-    */
+     * @const
+     * @type {number}
+     */
     this.pointerId = 'pointerId' in eventDict ? eventDict['pointerId'] : 0;
 
     /**
-    * @type {number}
-    */
+     * @type {number}
+     */
     this.width = 'width' in eventDict ? eventDict['width'] : 0;
 
     /**
-    * @type {number}
-    */
+     * @type {number}
+     */
     this.height = 'height' in eventDict ? eventDict['height'] : 0;
 
     /**
-    * @type {number}
-    */
+     * @type {number}
+     */
     this.tiltX = 'tiltX' in eventDict ? eventDict['tiltX'] : 0;
 
     /**
-    * @type {number}
-    */
+     * @type {number}
+     */
     this.tiltY = 'tiltY' in eventDict ? eventDict['tiltY'] : 0;
 
     /**
-    * @type {string}
-    */
+     * @type {string}
+     */
     this.pointerType = 'pointerType' in eventDict ? eventDict['pointerType'] : '';
 
     /**
-    * @type {number}
-    */
+     * @type {number}
+     */
     this.hwTimestamp = 'hwTimestamp' in eventDict ? eventDict['hwTimestamp'] : 0;
 
     /**
-    * @type {boolean}
-    */
+     * @type {boolean}
+     */
     this.isPrimary = 'isPrimary' in eventDict ? eventDict['isPrimary'] : false;
 
     // keep the semantics of preventDefault
@@ -202,10 +201,10 @@ class PointerEvent {
   }
 
   /**
-  * @private
-  * @param {Object.<string, ?>} eventDict The event dictionary.
-  * @return {number} Button indicator.
-  */
+   * @private
+   * @param {Object.<string, ?>} eventDict The event dictionary.
+   * @return {number} Button indicator.
+   */
   getButtons_(eventDict) {
     // According to the w3c spec,
     // http://www.w3.org/TR/DOM-Level-3-Events/#events-MouseEvent-button
@@ -243,11 +242,11 @@ class PointerEvent {
   }
 
   /**
-  * @private
-  * @param {Object.<string, ?>} eventDict The event dictionary.
-  * @param {number} buttons Button indicator.
-  * @return {number} The pressure.
-  */
+   * @private
+   * @param {Object.<string, ?>} eventDict The event dictionary.
+   * @param {number} buttons Button indicator.
+   * @return {number} The pressure.
+   */
   getPressure_(eventDict, buttons) {
     // Spec requires that pointers without pressure specified use 0.5 for down
     // state and 0 for up state.
@@ -261,8 +260,6 @@ class PointerEvent {
   }
 }
 
-inherits(PointerEvent, Event);
-
 
 /**
  * Checks if the `buttons` property is supported.
diff --git a/src/ol/pointer/PointerEventHandler.js b/src/ol/pointer/PointerEventHandler.js
index aa9becd009..a7a350129d 100644
--- a/src/ol/pointer/PointerEventHandler.js
+++ b/src/ol/pointer/PointerEventHandler.js
@@ -1,6 +1,7 @@
 /**
  * @module ol/pointer/PointerEventHandler
  */
+
 // Based on https://github.com/Polymer/PointerEvents
 
 // Copyright (c) 2013 The Polymer Authors. All rights reserved.
@@ -31,7 +32,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-import {inherits} from '../util.js';
 import {listen, unlisten} from '../events.js';
 import EventTarget from '../events/EventTarget.js';
 import {POINTER, MSPOINTER, TOUCH} from '../has.js';
@@ -83,14 +83,13 @@ const CLONE_PROPS = [
 ];
 
 
-/**
- * @constructor
- * @extends {module:ol/events/EventTarget}
- * @param {Element|HTMLDocument} element Viewport element.
- */
-class PointerEventHandler {
+class PointerEventHandler extends EventTarget {
+
+  /**
+   * @param {Element|HTMLDocument} element Viewport element.
+   */
   constructor(element) {
-    EventTarget.call(this);
+    super();
 
     /**
      * @const
@@ -416,6 +415,4 @@ class PointerEventHandler {
   }
 }
 
-inherits(PointerEventHandler, EventTarget);
-
 export default PointerEventHandler;
diff --git a/src/ol/pointer/TouchSource.js b/src/ol/pointer/TouchSource.js
index 92d34fa54d..b5331144a4 100644
--- a/src/ol/pointer/TouchSource.js
+++ b/src/ol/pointer/TouchSource.js
@@ -1,6 +1,7 @@
 /**
  * @module ol/pointer/TouchSource
  */
+
 // Based on https://github.com/Polymer/PointerEvents
 
 // Copyright (c) 2013 The Polymer Authors. All rights reserved.
@@ -31,7 +32,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-import {inherits} from '../util.js';
 import {remove} from '../array.js';
 import EventSource from '../pointer/EventSource.js';
 import {POINTER_ID} from '../pointer/MouseSource.js';
@@ -42,28 +42,75 @@ import {POINTER_ID} from '../pointer/MouseSource.js';
  */
 const CLICK_COUNT_TIMEOUT = 200;
 
-
 /**
  * @type {string}
  */
 const POINTER_TYPE = 'touch';
 
+/**
+ * Handler for `touchstart`, triggers `pointerover`,
+ * `pointerenter` and `pointerdown` events.
+ *
+ * @this {module:ol/pointer/TouchSource}
+ * @param {TouchEvent} inEvent The in event.
+ */
+function touchstart(inEvent) {
+  this.vacuumTouches_(inEvent);
+  this.setPrimaryTouch_(inEvent.changedTouches[0]);
+  this.dedupSynthMouse_(inEvent);
+  this.clickCount_++;
+  this.processTouches_(inEvent, this.overDown_);
+}
 
 /**
- * @constructor
- * @param {module:ol/pointer/PointerEventHandler} dispatcher The event handler.
- * @param {module:ol/pointer/MouseSource} mouseSource Mouse source.
- * @extends {module:ol/pointer/EventSource}
+ * Handler for `touchmove`.
+ *
+ * @this {module:ol/pointer/TouchSource}
+ * @param {TouchEvent} inEvent The in event.
  */
-class TouchSource {
+function touchmove(inEvent) {
+  inEvent.preventDefault();
+  this.processTouches_(inEvent, this.moveOverOut_);
+}
+
+/**
+ * Handler for `touchend`, triggers `pointerup`,
+ * `pointerout` and `pointerleave` events.
+ *
+ * @this {module:ol/pointer/TouchSource}
+ * @param {TouchEvent} inEvent The event.
+ */
+function touchend(inEvent) {
+  this.dedupSynthMouse_(inEvent);
+  this.processTouches_(inEvent, this.upOut_);
+}
+
+/**
+ * Handler for `touchcancel`, triggers `pointercancel`,
+ * `pointerout` and `pointerleave` events.
+ *
+ * @this {module:ol/pointer/TouchSource}
+ * @param {TouchEvent} inEvent The in event.
+ */
+function touchcancel(inEvent) {
+  this.processTouches_(inEvent, this.cancelOut_);
+}
+
+
+class TouchSource extends EventSource {
+
+  /**
+   * @param {module:ol/pointer/PointerEventHandler} dispatcher The event handler.
+   * @param {module:ol/pointer/MouseSource} mouseSource Mouse source.
+   */
   constructor(dispatcher, mouseSource) {
     const mapping = {
-      'touchstart': this.touchstart,
-      'touchmove': this.touchmove,
-      'touchend': this.touchend,
-      'touchcancel': this.touchcancel
+      'touchstart': touchstart,
+      'touchmove': touchmove,
+      'touchend': touchend,
+      'touchcancel': touchcancel
     };
-    EventSource.call(this, dispatcher, mapping);
+    super(dispatcher, mapping);
 
     /**
      * @const
@@ -269,20 +316,6 @@ class TouchSource {
     }
   }
 
-  /**
-   * Handler for `touchstart`, triggers `pointerover`,
-   * `pointerenter` and `pointerdown` events.
-   *
-   * @param {TouchEvent} inEvent The in event.
-   */
-  touchstart(inEvent) {
-    this.vacuumTouches_(inEvent);
-    this.setPrimaryTouch_(inEvent.changedTouches[0]);
-    this.dedupSynthMouse_(inEvent);
-    this.clickCount_++;
-    this.processTouches_(inEvent, this.overDown_);
-  }
-
   /**
    * @private
    * @param {TouchEvent} browserEvent The event.
@@ -299,16 +332,6 @@ class TouchSource {
     this.dispatcher.down(inPointer, browserEvent);
   }
 
-  /**
-   * Handler for `touchmove`.
-   *
-   * @param {TouchEvent} inEvent The in event.
-   */
-  touchmove(inEvent) {
-    inEvent.preventDefault();
-    this.processTouches_(inEvent, this.moveOverOut_);
-  }
-
   /**
    * @private
    * @param {TouchEvent} browserEvent The event.
@@ -343,17 +366,6 @@ class TouchSource {
     pointer.outTarget = event.target;
   }
 
-  /**
-   * Handler for `touchend`, triggers `pointerup`,
-   * `pointerout` and `pointerleave` events.
-   *
-   * @param {TouchEvent} inEvent The event.
-   */
-  touchend(inEvent) {
-    this.dedupSynthMouse_(inEvent);
-    this.processTouches_(inEvent, this.upOut_);
-  }
-
   /**
    * @private
    * @param {TouchEvent} browserEvent An event.
@@ -366,16 +378,6 @@ class TouchSource {
     this.cleanUpPointer_(inPointer);
   }
 
-  /**
-   * Handler for `touchcancel`, triggers `pointercancel`,
-   * `pointerout` and `pointerleave` events.
-   *
-   * @param {TouchEvent} inEvent The in event.
-   */
-  touchcancel(inEvent) {
-    this.processTouches_(inEvent, this.cancelOut_);
-  }
-
   /**
    * @private
    * @param {TouchEvent} browserEvent The event.
@@ -420,7 +422,4 @@ class TouchSource {
   }
 }
 
-inherits(TouchSource, EventSource);
-
-
 export default TouchSource;