IntersectionObserver, how to Intersect full height of elements observing using Javascript

0
votes

hello there i have a problem. i want to full intersect of selected observing element height. not half or double intersect like below in the picture two elements has been intersected when im scrolling i want only who is full height when i scroll

enter image description here

here is my HTML code

<ul>
  <li><a href="#one" class="active">P1</a></li>
  <li><a href="#two">P2</a></li>
  <li><a href="#three">P3</a></li>
  <li><a href="#four">P4</a></li>
</ul>
<div id="one">
  <p>P1 </p>
  <section>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
  tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
  quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo
  consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse
  cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non
  proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</section>
</div>

<div id="two">
  <p>P2 </p>
  <section>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
  tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
  quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo
  consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse
  cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non
  proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</section>
</div>

<div id="three">
  <p>P3 </p>
  <section>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
  tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
  quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo
  consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse
  cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non
  proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</section>
</div>

<div id="four">
  <p>P4 </p>
  <section>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
  tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
  quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo
  consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse
  cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non
  proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</section>
</div>

here is my Javascript code

  let observer = new IntersectionObserver(beTouching)

  document.querySelectorAll('div').forEach(div=>{
    observer.observe(div)
  })

  function beTouching(elements){
    elements.forEach(element=>{
      if(element.isIntersecting&&element.boundingClientRect.height){
        console.log(element.target)
         let id  = element.target.getAttribute('id')
         document.querySelector('ul li a[href*='+id+']').classList.add('active');
      }else{
        let id  = element.target.getAttribute('id')
         document.querySelector('ul li a[href*='+id+']').classList.remove('active');
      }
    })
  }

here is my Css code

*{
  padding: 0;
  margin: 0;
  box-sizing: border-box;
  text-decoration: none;
  scroll-behavior: smooth;

}
body{

}
div#one{
  background: cornflowerblue;
  height: 100vh;
}
div#two{
  background: coral;
  height: 100vh;
}
div#three{
  background: pink;
  height: 100vh;
}
div#four{
  background: skyblue;
  height: 100vh;
}
.active{
  background: red !important;
  color: white !important;
  padding: 20px;
}
ul{
  height: 50px;
  width: 100%;
  background: green;
  display: flex;
  list-style-type: none;
  justify-content: space-around;
  align-items: center;
  position: sticky;
  top: 0px;
}
javascript