如何使用javascript从浏览器中打开的PDF调用Rest服务？

<input type="file" id="pdfFileInput">

<script>
  const fileInput = document.getElementById('pdfFileInput');
  fileInput.addEventListener('change', handleFileSelect, false);

  function handleFileSelect(event) {
    const file = event.target.files[0];
    if (file.type === 'application/pdf') {
      // 调用REST服务发送PDF文件
      sendPDFToRestService(file);
    } else {
      alert('请选择一个PDF文件');
    }
  }

  function sendPDFToRestService(file) {
    // 创建FormData对象，用于发送文件数据
    const formData = new FormData();
    formData.append('pdfFile', file);

    // 创建XMLHttpRequest对象，发送POST请求
    const xhr = new XMLHttpRequest();
    xhr.open('POST', 'https://your-rest-service-url.com/upload', true);
    xhr.onreadystatechange = function() {
      if (xhr.readyState === 4 && xhr.status === 200) {
        // 处理REST服务的响应
        const response = JSON.parse(xhr.responseText);
        console.log(response);
      }
    };
    xhr.send(formData);
  }
</script>