聪明办法

var li = $('#test-div>ul>li');
li.remove(); //先删除
var ul = $('#test-div>ul');
var data = ['JavaScript','Lua','Pascal','Python','Ruby','Swift'];//定义数组
data2 = data.sort();//排序数组
for (let i of data2) ul.append($('<li><span>' + i + '</span></li>'));//append

笨办法

var js = $('#test-div>ul>li:first-child');

js.after('<li><span>Lua</span></li>');

var py = $('#test-div>ul>li:nth-child(3)');

py.before('<li><span>Pascal</span></li>');

var py = $('#test-div>ul>li:last-child');

py.before('<li><span>Ruby</span></li>');