 mr-2">Demo</h5>
    <button class="btn btn-link btn-sm reset">Reset</button>
    <button class="btn btn-link btn-sm source">View Source</button>
  </div>

  <p class="card-body">
    <span ts-data="a=1&b=2&c=3">
      <!-- empty c removes previous values of c and then adds 5 -->
      <a href="/data" ts-data="b=4&c&c=5" ts-req ts-req-method="post">So. Much. Data.</a>
    </span>
  </p>

  <script>
    XHRMock.post("/data", function(req, res) {
      return res.status(200).body('<span>' + new URLSearchParam