Adding scroll to plugin

src/modules/webslides.js

@@ -185,7 +185,7 @@ export default class WebSlides {
       }
 
       DOM.unlockScroll();
-      callback.call(this, nextSlide);
+      setTimeout(() => { callback.call(this, nextSlide); }, 150);
     });
   }
 

src/plugins/scroll.js

@@ -0,0 +1,50 @@
+import ScrollHelper from '../utils/scroll-to';
+
+const MIN_WHEEL_DELTA = 40;
+
+export default class Scroll {
+  /**
+   * Scroll handler for the WebSlides.
+   * @param {WebSlides} wsInstance The WebSlides instance
+   */
+  constructor(wsInstance) {
+    /**
+     * @type {WebSlides}
+     * @private
+     */
+    this.ws_ = wsInstance;
+
+    this.scrollContainer_ = ScrollHelper.getScrollableContainer();
+    this.isGoingUp_ = false;
+
+    if (this.ws_.isVertical) {
+        this.scrollContainer_.addEventListener(
+            'wheel', this.onMouseWheel_.bind(this));
+    }
+  }
+
+  /**
+   * Reacts to the wheel event. Detects whether is going up or down and decides
+   * if it needs to move the slide based on the amount of delta.
+   * @param {WheelEvent} event The Wheel Event.
+   * @private
+   */
+  onMouseWheel_(event) {
+    if (this.ws_.isMoving) {
+      return;
+    }
+
+    const { deltaY: wheelDelta } = event;
+    this.isGoingUp_ = wheelDelta < 0;
+
+    if (Math.abs(wheelDelta) >= MIN_WHEEL_DELTA) {
+      if (this.isGoingUp_) {
+        this.ws_.goPrev();
+      } else {
+        this.ws_.goNext();
+      }
+
+      event.preventDefault();
+    }
+  }
+};

src/utils/scroll-to.js

@@ -1,6 +1,6 @@
 import Easings from './easing';
 
-let SCROLLABLE_CONTAINER;
+let SCROLLABLE_CONTAINER = getScrollableContainer();
 
 /**
  * Returns the correct DOM element to be used for scrolling the