CODE EXAMPLE FOR JAVASCRIPT

fade in and fadeout animation

.elementToFadeInAndOut {
    width:200px;
    height: 200px;
    background: red;
    -webkit-animation: fadeinout 4s linear forwards;
    animation: fadeinout 4s linear forwards;
}

@-webkit-keyframes fadeinout {
  0%,100% { opacity: 0; }
  50% { opacity: 1; }
}

@keyframes fadeinout {
  0%,100% { opacity: 0; }
  50% { opacity: 1; }
}