Answers for "vanilla js fade in css"

vanilla javascript fade out

<div id="target">Click to fade</div>
<script>
  function fadeOutEffect() {
    var fadeTarget = document.getElementById("target");
    var fadeEffect = setInterval(function () {
        if (!fadeTarget.style.opacity) {
            fadeTarget.style.opacity = 1;
        }
        if (fadeTarget.style.opacity > 0) {
            fadeTarget.style.opacity -= 0.1;
        } else {
            clearInterval(fadeEffect);
        }
    }, 200);
}

document.getElementById("target").addEventListener('click', fadeOutEffect)
</script>
<style>
  #target {
    height: 100px;
    background-color: red;
}
</style>

fade effect with javascript

<script type="text/javascript" src="Fader.js"></script>