How to clear previous data in an infinite scroll

Question

I have coded an infinite scroll. When the user scrolls it will load an additional 20 items which makes it a long list.

I want the scroll to loads new items and clear the previous items.

var listElm = document.querySelector('#infinite-list');

// Add 20 items.
var nextItem = 1;
var loadMore = function() {
  for (var i = 0; i < 20; i++) {
    var item = document.createElement('li');
    item.innerText = 'Item ' + nextItem++;
    listElm.appendChild(item);
  }
}

// Detect when scrolled to bottom.
listElm.addEventListener('scroll', function() {
  if (listElm.scrollTop + listElm.clientHeight >= listElm.scrollHeight) {
    loadMore();
  }
});

// Initially load some items.
loadMore();

#infinite-list {
  /* We need to limit the height and show a scrollbar */
  width: 200px;
  height: 300px;
  overflow: auto;

  /* Optional, only to check that it works with margin/padding */
  margin: 30px;
  padding: 20px;
  border: 10px solid black;
}

/* Optional eye candy below: */
li {
  padding: 10px;
  list-style-type: none;
}
li:hover {
  background: #ccc;
}

<ul id='infinite-list'>
</ul>

when I execute your code, the items kept increasing when I scroll down. Can you elaborate on what's the problem is? — Fernand
@Fernand I want to when I scroll down the list only show 20 items — kalipts
When the app load the new items it have to remove the old items — kalipts
So what you want to happen is that when the users scrolls to the bottom, the old items are deleted from the list and only the new ones stay? — Franco Altuna

djcaesar9114 djcaesar9114 · Accepted Answer · 2020-04-14T03:21:19

If you empty the list before that, would it be ok?

var listElm = document.querySelector('#infinite-list');

// Add 20 items.
var nextItem = 1;
var loadMore = function() {
  listElm.innerHTML = ''
  for (var i = 0; i < 20; i++) {
    var item = document.createElement('li');
    item.innerText = 'Item ' + nextItem++;
    listElm.appendChild(item);
  }
}

// Detect when scrolled to bottom.
listElm.addEventListener('scroll', function() {
  if (listElm.scrollTop + listElm.clientHeight >= listElm.scrollHeight ) {
    loadMore();
  }
});

// Initially load some items.
loadMore();

#infinite-list {
  /* We need to limit the height and show a scrollbar */
  width: 200px;
  height: 300px;
  overflow: auto;

  /* Optional, only to check that it works with margin/padding */
  margin: 30px;
  padding: 20px;
  border: 10px solid black;
}

/* Optional eye candy below: */
li {
  padding: 10px;
  list-style-type: none;
}
li:hover {
  background: #ccc;
}

<ul id='infinite-list'>
</ul>

How to clear previous data in an infinite scroll

2 Answers