filter within a filter javacript code example

Example 1: how the filter() function works javascript

const arr = [1, 2, 3, 4, 5, 6, 7, 8, 9];

const filter = arr.filter((number) => number > 5);
console.log(filter); // [6, 7, 8, 9]

Example 2: filter items javascript

// Filter items
function filterItems(e) {
  // Convert to lowercase
  var text = e.target.value.toLowerCase();
  // Get lis
  var items = itemList.getElementsByTagName('li');
  // Convert to an array
  Array.from(items).forEach(function(item) {
    var itemName = item.firstChild.textContent;
    if (itemName.toLowerCase().indexOf(text) != -1) {
      item.style.display = 'block';
    } else {
      item.style.display = 'none';
    }
  });
}