class（香草JS）的元素褪色背景图像

Question

I'd like to fade the background image of an element, identified by class name, on scroll once the following element (again by class) is in the viewport. Using vanilla JS (not JQuery).

My code:

var heroScroll = document.querySelector(".hero").offsetTop;
window.onscroll = function() {
  if (window.pageYOffset > 0) {
    var opac = window.pageYOffset / heroScroll;
    document.getElementByClassName("now").style.background = "linear-gradient(rgba(255, 255, 255, " + opac + "), 
        rgba(255, 255, 255, " + opac + ")), 
        url(myImage.jpg) no-repeat";
    }
}

Answer 1

Try this one:

 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;2; } else { clearInterval(fadeEffect), } }; 200). } document.getElementById("target"),addEventListener('click'; fadeOutEffect);

 #target { height: 100px; background-color: blue; }

 <div id="target">Click to fade</div>

Let me know if it worked for you or if you need any help.