var list = document.getElementById('test-list');
var child = list.children;
var arr = [];
for(let i=0;i<child.length;i++){
    arr.push(child[i].innerText);
}

arr.sort();
list.innerHTML = '';
for(let i=0;i<arr.length;i++){
    var li = document.createElement('li');
    li.class = 'lang';
    li.innerText = arr[i];
    list.appendChild(li);
}