Slide Halaman Vertikal dengan Slick Slider

jQuery(document).ready(function(){

  const slider = jQuery('.vertical_slider');
  
  //slickify function for re-construct slick in different device size https://stackoverflow.com/a/32100492
  function slickify(){
  
	slider.slick({
      slide:'.page_section',
      infinite: false,
      arrows:true,
      prevArrow:'.page_arrow_up_wrapper',
      nextArrow:'.page_arrow_down_wrapper',
      verticalSwiping:true,
      fade:false,
      dots:false,
      autoplay:false,
      vertical:true,
      responsive: [
            {
                breakpoint: 991,
                settings: "unslick"
            }
        ]
    });
  }
  
slickify();
jQuery(window).resize(function(){
    var $windowWidth = jQuery(window).width();
    if ($windowWidth > 991) {
        slickify();   
    }
});

//for mouse wheel activation    
slider.on('wheel', (function(e) {
  e.preventDefault();

  if (e.originalEvent.deltaY < 0) {
    jQuery(this).slick('slickPrev');
  } else {
    jQuery(this).slick('slickNext');
  }
}));

  
  //for header/element manipulation, add class if first slide active
  slider.on('afterChange', function(event, slick, currentSlide){
    if (currentSlide === 0) {
        console.log('First Slide');
        jQuery('header').eq(currentSlide).addClass('first_slide_active');
      
    } else {
        jQuery('header').removeClass('first_slide_active');
      console.log('Not First Slide');
    }
  });




  
});