node_modules/material-design-lite/src/progress/snippets/progress-buffering.html

<!-- MDL Progress Bar with Buffering -->
<div id="p3" class="mdl-progress mdl-js-progress"></div>
<script>
  document.querySelector('#p3').addEventListener('mdl-componentupgraded', function() {
    this.MaterialProgress.setProgress(33);
    this.MaterialProgress.setBuffer(87);
  });
</script>