Скролл с секциями и блоками

$('#myContainer').bind('mousewheel', function(e) { 
  var sec_1 = $(".section"); 
  let main__current = $('.main__current'); 
  if (e.originalEvent.wheelDelta / 120 > 0) { 
    if (main__current.is(':first-child')) { 
      return; 
    } 
    main__current.removeClass("main__current").addClass("main__next") 
    main__current.prev().addClass("main__current").removeClass("main__next main__previous") 
     
  } else { 
    if (main__current.is(':last-child')) { 
      return; 
    } 
    main__current.removeClass("main__current").addClass("main__previous"); 
    main__current.next().addClass("main__current").removeClass("main__next main__previous") 
  } 
});

body { 
  overflow: hidden 
} 
 
.main__section { 
  position: absolute; 
  left: 0; 
  width: 100vw; 
  height: 100vh; 
  -webkit-transition: top .3s linear; 
  transition: top .3s linear; 
  overflow: hidden; 
} 
.main__section  > div { 
  position: absolute; 
  left: 0; 
  top: 100%; 
  width: 100vw; 
  height: 100vh; 
  -webkit-transition: top .3s linear; 
  transition: top .3s linear; 
} 
.main__section  > div.prev { 
    top: -100% 
} 
.main__section  > div.active { 
    top: 0 
} 
.main__previous { 
  top: -100%; 
} 
 
.main__current { 
  z-index: 1; 
  top: 0; 
} 
 
.main__next { 
  top: 100%; 
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 
<div id="myContainer"> 
  <div class="section section_1 main__section main__current"> 
    1 
  </div> 
  <div class="section section_2 main__section main__next"> 
    2 
  </div> 
  <div class="section section_3 main__section main__next"> 
    <div class="prev"> Блок 1</div> 
    <div  class="active"> Блок 2</div> 
    <div> Блок 3</div> 
    <div> Блок 4</div> 
 
  </div> 
  <div class="section section_2 main__section main__next"> 
    4 
  </div> 
</div>