ask/app/views/admin/asks/print.html.erb

<script src="https://code.jquery.com/jquery-3.4.1.slim.min.js">
</script>
<script src="https://html2canvas.hertzen.com/dist/html2canvas.js"></script>
<%= javascript_include_tag "jspdf.min" %>
<style>
  input[type="button"],button,input[type="submit"] {
    outline: 0;
    border-radius: 1.3em;
    background: #d9e4f7;
    font-weight: bold;
    outline: 0;
  }
  input[type="button"]:hover,button:hover,input[type="submit"]:hover {
    background: #be8a8a;
  }
  .print_text{
    padding: 2em;
    width: 650px;
    margin: auto;
  }
  @media print
  {    
    .no-print, .no-print *
    {
        display: none !important;
    }
  }
</style>
<script type="text/javascript">
  function save_data(){
    var filename  = '<%= @save_name %>.pdf';
    $('div.print_text').find('input[type=button]').hide()
    html2canvas($('div.print_text')[0]).then(canvas => {
      var pdf = new jsPDF('px', 'mm', 'a4');
      var width = pdf.internal.pageSize.getWidth()-3;
      var height = $('div.print_text').innerHeight()/$('div.print_text').innerWidth()*width;
      pdf.addImage(canvas.toDataURL('image/png'), 'PNG', 0, 0,width ,height );
      pdf.save(filename);
    });
    $('div.print_text').find('input[type=button]').show()
  }
</script>
<div class="no-print" style="text-align: center;">
  <input onclick="save_data()" value="<%= I18n.t('ask.save_data') %>" type="button">
</div>
<div class="print_text">
<%= @print_text.html_safe %>
</div>