javascript get user from api

1            fetch('https://jsonplaceholder.typicode.com/users')
2        .then(function (response) {
3            return response.json();
4        })
5        .then(function (data) {
6            appendData(data);
7        })
8        .catch(function (err) {
9            console.log('error: ' + err);
10        });
11
12    function appendData(data) {
13        var mainContainer = document.getElementById("users");
14        for (var i = 0; i < data.length; i++) {
15            var li = document.createElement("li");
16            li.innerHTML =  data[i].username;
17            li.classList.add('item');
18            li.dataset.userId = data[i].id;
19            li.addEventListener('click', (event) => getPosts(event))
20            mainContainer.appendChild(li);
21        }
22
23    }
24
25    function cleanPosts() {
26        var users = document.querySelectorAll('.item ul');
27        for(var i = 0; i < users.length; i++) {
28            if(users[i]) {
29                users[i].style.display = 'none';
30            }
31        }
32    }
33
34    function getPosts(event) {
35
36        var userId = event.target.dataset.userId;
37
38        fetch(`https://jsonplaceholder.typicode.com/posts?userId=${userId}`)
39            .then(response => response.json())
40            .then(json => renderPosts(json, event.target))
41    }
42
43    function renderPosts(posts, target) {
44        var postsList = target.childNodes[1];
45
46        cleanPosts();
47
48        if(postsList){
49            postsList.style.display = 'block';
50        } else {
51            var list = document.createElement("ul");
52
53            for (var i = 0; i < posts.length; i++) {
54
55                var item = document.createElement("li");
56                var liTitle = document.createElement("strong");
57                var liBody = document.createElement("p");
58
59                liTitle.innerHTML = posts[i].title;
60                liBody.innerHTML = posts[i].body;
61
62                item.appendChild(liTitle);
63                item.appendChild(liBody);
64                list.appendChild(item);
65            }
66
67            target.appendChild(list);
68        }
69
70    }
71