JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
<div id="s1">
  Секция 1
</div>
<div id="s2">
  Секция 2
</div>
<div id="s3">
  Секция 3
</div>
<div id="s4">
  Секция 4
</div>
<div id="s5">
  Секция 5
 </div>
<div id="s6">
  Секция 6
</div>

CSS

body {
  margin: 0;
  padding: 0;
}

div {
  width: 100%;
  height: 300px;
  padding-top: 10px;
  padding-left: 20px;
  box-sizing: border-box;
  color: #ffffff;
}

#s1 {
  background-color: #ff8080;
  height: 100vh;
}
#s2 {
  background-color: orange;
  height: 100vh;
}
#s3 {
  background-color: yellow;
  height: 100vh;
}
#s4 {
  background-color: yellowgreen;
  height: 100vh;
}
#s5 {
  background-color: lightgreen;
  height: 100vh;
}
#s6 {
  background-color: red;
}

a {
  display: block;
  margin-top: 50px;
}

JavaScript

var currentAnchor = 0;
            var isAnimating  = false;

            function scrollUpDown(dir) {

            var sections = $('#s1, #s2, #s3, #s4, #s5, #s6');
            var currentScroll = $(document).scrollTop();
            var nearestEl = null;
            var defaultTop = 0;

            sections.each(function(i, el) {

                var el = $(el);

                if (dir == 'down') {
                    if (currentScroll < el.offset().top) {
                        if (nearestEl != null && nearestEl.offset().top > el.offset().top) {
                            nearestEl = el;
                        } else if (nearestEl == null) {
                            nearestEl = el;
                        }
                    }
                    defaultTop = $(document).outerHeight(true);
                }

                if (dir == 'up') {
                    if (currentScroll > el.offset().top) {
                        if (nearestEl != null && nearestEl.offset().top < el.offset().top) {
                            nearestEl = el;
                        } else if (nearestEl == null) {
                            nearestEl = el;
                        }
                    }
                    var defaultTop = 0;
                }

            });

            if (nearestEl != null) {
                return(nearestEl.offset().top);
            } else {
                        return(defaultTop);
                    }
            }

            $(function(){
                $('body').on('wheel', function(e){
                    e.preventDefault();
                    e.stopPropagation();
                    if( isAnimating ) {
                        return false;
                    }
                    isAnimating  = true;
                    // Increase or reset current anchor
                    if( e.originalEvent.deltaY < 0 ) {
                        currentAnchor = scrollUpDown('up');
                    } else{
                       ...