var parent_node, 
    children_nodes, 
    arr = [];

parent_node = document.querySelector('#test-list');
children_nodes = parent_node.children;
for (var i = 0; i < children_nodes.length; i ++) {
    arr.push(children_nodes[i]);
}

arr.sort(function (x, y) {
    if (x.innerText < y.innerText) {
      return -1;
    }
    else {
      return 1;
    }
});

for (var node of arr) {
    parent_node.appendChild(node);
}