如何将 onclick 事件添加到动态生成的 HTML 元素

Question

Im trying to develop a chat app that allows for users to create a new chat room.

I already have code that runs for each item in the list, on click, will add users to the new room

Javascript:

document.querySelectorAll('.select-room').forEach(li => {
    li.onclick = () => {
        let newroom = li.innerHTML;
        if (newroom == room){
            msg = `You are already in ${room} room.`
            printSysMsg(msg);
        } else {
            leaveRoom(room);
            joinRoom(newroom);
            room = newroom;
        }
    }
});

HTML:

            <nav id='sidebar'>
            <h4>ROOMS</h4>
            <ul id='room_list' >
                {% for room in rooms %}
                    <li class = 'select-room'>{{ room }}</li>
                {% endfor %}
            </ul>                
        </nav>

However, when i add new rooms, im not able to click on the list item straight away to change chat rooms, i would have to refresh the page.

Any help would be greatly appreciated

Answer 1

Have you tried adding an event listener? So in your forEach:

 document.querySelectorAll('.select-room').forEach(li => { li.addEventListener('click', () => { let newroom = li.innerHTML; if (newroom == room){ msg = `You are already in ${room} room.` printSysMsg(msg); } else { leaveRoom(room); joinRoom(newroom); room = newroom; } }) });

Answer 2

You have to add the event listener again to each element you add. But not like JakeCroth tried to explain (at least if I understand you correctly). Instead, try it like this:

 let lst = document.querySelector('.lst'); let btn = document.querySelector('.btn'); function addListItem() { let li = document.createElement('li'); li.innerHTML = "New element"; li.addEventListener('click', testTheEventListener); lst.appendChild(li); } function testTheEventListener() { console.log("The event listener works!"); } document.querySelectorAll('li').forEach(li => { li.addEventListener('click', () => { testTheEventListener(); }); });

 <ul class='lst'> <li class="listItem">First</li> <li class="listItem">Second</li> <li class="listItem">Third</li> </ul> <button onclick="addListItem()" class='btn'>Add item</button>

So as you can see I add the event listener to all existing items:

document.querySelectorAll('li').forEach(li => {
  li.addEventListener('click', () => {
    testTheEventListener();
  });
});

And if an item gets added dynamically I add the event listener to this item as well.

function addListItem() {
  let li = document.createElement('li');

  li.innerHTML = "New element";  
  li.addEventListener('click', testTheEventListener); //<--
  lst.appendChild(li);
}

If I understood you wrong, just feel free to correct me.