code: function processPointerPosition(e) {
      var prevValue = this.value;
  
      if (this.style === 'horizontal') {
        this.__value = (e.clientX - this.rect.left) / this.rect.width;
      } else {
        this.__value = 1 - (e.clientY - this.rect.top) / this.rect.height;
      }
  
      // clamp __value, which is only used internally
      if (this.__value > 1) this.__value = 1;
      if (this.__value < 0) this.__value = 0;
  
      var shouldDraw = this.output();
  
      if (shouldDraw) this.draw();
    }
docs: Generates a value between 0-1 given the current pointer position in relation
  to the Slider's position, and triggers output.
  @instance
  @memberof Slider
  @param {PointerEvent} e - The pointer event to be processed.