var myVar;

function myFunction() {
  document.getElementById("loader").style.display = "block";
  document.getElementById("myDiv").style.display = "none";
  myVar = setTimeout(showPage, 3000);
}

function showPage() {
  document.getElementById("loader").style.display = "none";
  document.getElementById("myDiv").style.display = "block";
}

/* Center the loader */

#loader {
  position: absolute;
  display: none;
  left: 50%;
  top: 50%;
  z-index: 1;
  width: 100px;
  height: 100px;
  margin: -50px 0 0 -50px;
  border: 10px solid #3498db;
  border-radius: 50%;
  border-top: 10px solid #f3f3f3;
  -webkit-animation: spin 2s linear infinite;
  animation: spin 2s linear infinite;
}

@-webkit-keyframes spin {
  0% {
    -webkit-transform: rotate(0deg);
  }
  100% {
    -webkit-transform: rotate(360deg);
  }
}

@keyframes spin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}


#myDiv {
  display: none;
  text-align: center;
}

<a onclick="myFunction()" href="#" target="_self">Download</a>

<div id="loader"></div>

<div style="display:none;" id="myDiv" class="animate-bottom">
  <h2>Tada!</h2>
  <p>Some text in my newly loaded page..</p>
</div>