将按钮和对话框添加到 html

<button id="googleFormButton" class="mdl-button mdl-js-button mdl-button--raised">
  Load Form
</button>
<dialog id="googleFormsDialog" class="mdl-dialog">
  <!-- <h4 class="mdl-dialog__title">Google Form</h4> -->
  <div id="googleformparent" class="mdl-dialog__content">
    <div id="googleFormsDialogIFrameLoading">Loading...</div>
    <!-- IFrame element googleFormsDialogIFrame is added dynamically due to google forms popup issue. -->
  </div>
  <div class="mdl-dialog__actions">
    <button id="dialogclose" type="button" class="mdl-button">Close</button>
  </div>
</dialog>