<style>
#clamp {
  width: 100px;
  overflow: hidden;
  display: -webkit-box;
  -webkit-box-orient: block-axis;
}
</style>
<div id=clamp>This text should stay visible after setting line clamp on it.</div>
<script>
document.body.offsetHeight;
clamp.style.webkitLineClamp = '2';
</script>