code: function AlphaTransition( element ) {
  
    const _baseTransition = new BaseTransition( element, CLASSES );
  
    /**
     * @returns {AlphaTransition} An instance.
     */
    function init() {
      _baseTransition.init();
      const _transitionCompleteBinded = _transitionComplete.bind( this );
      _baseTransition.addEventListener(
        BaseTransition.END_EVENT,
        _transitionCompleteBinded
      );
      return this;
    }
  
    /**
     * Handle the end of a transition.
     */
    function _transitionComplete() {
      this.trigger( BaseTransition.END_EVENT, { target: this } );
    }
  
    /**
     * Fade to 100% by applying a utility alpha class.
     * @returns {AlphaTransition} An instance.
     */
    function fadeIn() {
      _baseTransition.applyClass( CLASSES.ALPHA_100 );
  
      return this;
    }
  
    /**
     * Fade to nothing by applying a utility alpha class.
     * @returns {AlphaTransition} An instance.
     */
    function fadeOut() {
      _baseTransition.applyClass( CLASSES.ALPHA_0 );
  
      return this;
    }
  
    // Attach public events.
    this.addEventListener = Events.addEventListener;
    this.trigger = Events.trigger;
    this.removeEventListener = Events.removeEventListener;
  
    this.animateOff = _baseTransition.animateOff;
    this.animateOn = _baseTransition.animateOn;
    this.halt = _baseTransition.halt;
    this.isAnimated = _baseTransition.isAnimated;
    this.remove = _baseTransition.remove;
    this.setElement = _baseTransition.setElement;
  
    this.fadeIn = fadeIn;
    this.fadeOut = fadeOut;
    this.init = init;
  
    return this;
  }
docs: AlphaTransition
  @class
  
  @classdesc Initializes new AlphaTransition behavior.
  
  @param {HTMLNode} element
  DOM element to apply opacity transition to.
  @returns {AlphaTransition} An instance.