/ CSS /
.reveal{position:relative;transform:translateX(200px);opacity:0;transition:1s all ease;}
.reveal.active{transform:translateX(0);opacity:1;}

/ JavaScript /

function reveal() {
  var reveals = document.querySelectorAll(".reveal");

  for (var i = 0; i < reveals.length; i++) {
    var windowHeight = window.innerHeight;
    var elementTop = reveals[i].getBoundingClientRect().top;
    var elementVisible = 150;

    if (elementTop < windowHeight - elementVisible) {
      reveals[i].classList.add("active");
    } else {
      reveals[i].classList.remove("active");
    }
  }
}

window.addEventListener("scroll", reveal);