addEventListener on a querySelectorAll() with classList

Evan picture Evan · Jun 1, 2018 · Viewed 29.9k times · Source

I am trying to add an event listener but no result came. I know JavaScript has a hoisting feature but I believe I tried all except the correct solution.

const cbox = document.querySelectorAll(".box");
function doit() {
  for (let i = 0; i < cbox.length; i++){
    cbox[i].classList.add("red");
  }
}
cbox.addEventListener("click", doit, false);

Can somebody spot the mistake I make?

Answer

Mamun picture Mamun · Jun 1, 2018

There are some dissimilarities between the code and the link you have provided. There is no function doit() in there. You have attached addEvenListener to the NodeList in cbox.addEventListener("click",.....

Try the following:

const cbox = document.querySelectorAll(".box");

 for (let i = 0; i < cbox.length; i++) {
     cbox[i].addEventListener("click", function() {
       cbox[i].classList.toggle("red");
     });
 }
*,
html,
body {
    padding: 0;
    margin: 0;
}

.box {
    width: 10rem;
    height: 10rem;
    background-color: yellowgreen;
    float: left;
    position: relative;
    margin: 0.5rem;
    transition: .5s all;
}

h3 {
    display: block;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

.box:not(:first-child) {
    margin-left: 1rem;
}

.red {
    background-color: orangered;
}
<div id="box1" class="box box1">
    <h3>Box 1</h3>
</div>
<div id="box2" class="box box2">
    <h3>Box 2</h3>
</div>
<div id="box3" class="box box3">
    <h3>Box 3</h3>
</div>
<div id="box4" class="box box4">
    <h3>Box 4</h3>
</div>