[Dilettante_Pro]

С использованием технологии j0hnik
Добавляете, меняете...

<ul class="list">
</ul>
<button  id = "add">Добавить</button >
<button  id = "stop">Хватит</button >
<script>
   var list = document.querySelector('.list');
   document.querySelector('#add').onclick = function() {
        document.querySelectorAll("li").forEach(el=>el.contentEditable = false);
        var el = document.createElement('li');
        el.innerHTML = "Type your task...";
        el.setAttribute("contenteditable",true);
        list.appendChild(el);
   }
    document.querySelector('#stop').onclick = function() {
        list.querySelectorAll("li").forEach(el=>el.contentEditable = false);
        this.style.display = "none";
        document.querySelector('#add').style.display = "none";
        list.querySelectorAll('li').forEach(el=>el.onclick = function(){
            alert(this.innerHTML)
        });
    }
 
</script>