css/css-transforms/css-transform-animate-translate-implied-y.html

<!DOCTYPE html>
<html>
  <head>
    <title>CSS Test (Transforms): Animating between translates where one has an implied `y` value</title>
    <link rel="author" title="Manish Goregaokar" href="mailto:manishearth@gmail.com">
    <meta name="assert" content='This tests that translate(x) is animated as if it were translate(x, 0px)'>
    <link rel=match href=css-transform-animate-translate-implied-y-ref.html>
    <link rel="help" href="https://drafts.csswg.org/css-transforms-1/#funcdef-transform-translate">
    <style>
    #box {
        background:red;
        width: 200px;
        height: 200px;
    }
    </style>
  </head>
  <body>
    <div id=box></div>
    <script>
        let anim = document.getElementById('box').animate([
            { transform: 'translate(180px)' },
            { transform: 'translate(20px, 0px)' }
        ], {
            duration: 1000,
        });
        anim.pause();
        anim.currentTime = 500;
    </script>
  </body>
</html>