[Aetae]

alena0309, всё работает:

<script>
let userJsonURL = 'users.json';
let users = [];
let nameFilter = `name`;

const nameFilterUpper = nameFilter.toUpperCase();
const wrapItemNameInSpan = (item) => `<span class="name">${item.name}</span>`;

const render = () => {
  document.body.innerHTML = users.filter((item) => {
    const itemNameUpper = item.name.toUpperCase();

    return !nameFilter || itemNameUpper.includes(nameFilterUpper)
  }).map(wrapItemNameInSpan).join(``);
}

// имитация users.json
userJsonURL = 'data:,' + JSON.stringify([
  {name: 'filtered'}, 
  {name: 'Vasya-name'}, 
  {name: 'Zlatan-name'}
]);

fetch(userJsonURL)
  .then((res) => res.json())
  .then((data) => users = data)
  .then(render);
</script>