I pick up on this question. What I have so far:

$('.lock').click(function () {
  $('.fa-lock', this).addClass('fa-flip');
  $('.fa-unlock', this).addClass('fa-flip');
  setTimeout(function () {
    $('.fa-lock').css('color', 'rgba(0, 0, 0, 0)');
    $('.fa-unlock').css('color', 'green');
  }, 1250);
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.0.0-beta2/js/all.min.js"></script>
<link href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.0.0-beta2/css/all.min.css" rel="stylesheet"/>
<div class="fa-5x fa-stack lock">
  <i class="fas fa-unlock fa-stack-1x" style="--fa-animation-duration: 5s; --fa-animation-iteration-count: 1; color: rgba(0, 0, 0, 0)"></i>
  <i class="fas fa-lock fa-stack-1x" style="--fa-animation-duration: 5s; --fa-animation-iteration-count: 1; color: red"></i>
</div>

<iframe name="sif1" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>

But only the last quarter of the green unlock icon animation should follow the visible red lock icon animation. How can I start the animation at 75 %?

Or would you do it all differently? Maybe without Font Awesome's animation functions?

CodePudding user response：

You need to override .fa-flip animation:

$('.lock').click(function() {
  $('.fa-lock', this).addClass('fa-flip');
  $('.fa-unlock', this).addClass('fa-flip');
  setTimeout(function() {
    $('.fa-lock').css('color', 'rgba(0, 0, 0, 0)');
    $('.fa-unlock').css('color', 'green');
  }, 600);
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.0.0-beta2/js/all.min.js"></script>
<link href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.0.0-beta2/css/all.min.css" rel="stylesheet" />
<style>
  @keyframes halfflip {
    to {
      transform: rotateY(360deg);
    }
  }
  
  .fa-flip {
    animation-name: halfflip;
    animation-timing-function: ease-in-out;
  }
  
</style>
<div class="fa-5x fa-stack lock">
  <i class="fas fa-unlock fa-stack-1x" style="--fa-animation-duration: 4s; --fa-animation-iteration-count: 1; color: transparent; animation-fill-mode: forwards; --fa-animation-delay:-2s"></i>
  <i class="fas fa-lock fa-stack-1x" style="--fa-animation-duration: 4s; --fa-animation-iteration-count: 1; color: red; animation-fill-mode: forwards; --fa-animation-delay:-2s"></i>
</div>

<iframe name="sif2" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>

I hope this is what you wanted.