Javascript - Addeventlistener On All Created Li Elements

Question

So I have a simple script that adds 'li' elements to the 'ul' and assigns them a class. Now I want to change the class of 'li' item on click event. Here is the HTML:

Solution 1:

Use event delegation for the dynamically created elements. With this, you only need one event listener on the ul#list and it will work for all elements you dynamically attach to it:

document.getElementById("list").addEventListener("click",function(e) {
  if (e.target && e.target.matches("li.item")) {
    e.target.className = "foo"; // new class name here
    }
});

Here's a simplified example so you can see what happens with the code:

function addItem(i) {
  var li = document.createElement('li');
  li.appendChild(document.createTextNode(i));
  li.className = 'item';
  document.getElementById('list').appendChild(li);
}

var counter = 2;
document.getElementById('btn').addEventListener('click', function() {
  addItem(counter++);
});

document.getElementById("list").addEventListener("click", function(e) {
  if (e.target && e.target.matches("li.item")) {
    e.target.className = "foo"; // new class name here
    alert("clicked " + e.target.innerText);
  }
});

<ul id="list">
  <li class="item">1</li>
</ul>

<button id="btn">
  add item
</button>

Solution 2:

You'll have to set the eventListener on each single item, as document.getElementsByClassName() returns a collection of items and you can't simply add an event listener to all of them with one call of addEventListener().

So, just like the loop you used in itemDone(), you'll have to iterate over all items and add the listener to them:

var items = document.getElementsByClassName("item");
for (var i = 0; i < items.length; i++) {
  items[i].addEventListener("click", itemDone);
}

As pointed out in the comments, you can also do so directly when creating the elements, so in your addItem() function, add:

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newListItem.addEventListener("click", itemDone);

Solution 3:

try this :

var item = document.getElementsByClassName("item");
for (var i = 0; i < item.length; i++) {
  item[i].addEventListener("click", itemDone);
}

Solution 4:

function addItem(i) {
  var li = document.createElement('li');
  li.appendChild(document.createTextNode(i));
  li.className = 'item';
  document.getElementById('list').appendChild(li);
}

var counter = 2;
document.getElementById('btn').addEventListener('click', function() {
  addItem(counter++);
});

document.getElementById("list").addEventListener("click", function(e) {
  if (e.target && e.target.matches("li.item")) {
    e.target.className = "foo"; // new class name here
    alert("clicked " + e.target.innerText);
  }
});

<ul id="list">
  <li class="item">1</li>
  <li class="item">1</li>
  <li class="item">1</li>
  <li class="item">1</li>
  <li class="item">1</li>
</ul>

<button id="btn">
  add item
</button>

Solution 5:

First, try using getElementByTagName instead of querySelectorAll, because querySelectorAll is slower. And second, item receives an array, so item.addEventListener will give you an error. You have to do the addEventListener over item[counter], in a loop.

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