javascript addeventlistener change code example

Example 1: js addeventlistener change select

<input id="test" type="text" value="Sélectionnez-moi !" />
<script>
  var elem = document.getElementById('test');
  elem.addEventListener('select', function() {
    alert('La sélection a changé !');
  }, false);
</script>

Example 2: addeventlistener js to change style

var button = document.querySelector("button");

button.addEventListener("click", function() {
    const curColour = document.body.style.backgroundColor;

    document.body.style.backgroundColor = curColour === 'red' ? 'blue' : 'red';
});

Example 3: addeventlistener js to change style

var button = document.querySelector("button");

button.addEventListener("click", function() {
    const curColour = document.body.style.backgroundColor;

    if (curColour === 'red') {
        document.body.style.backgroundColor = "blue";
    }
    else {
        document.body.style.backgroundColor = "red";
    }
});