在javascript中将响应从服务器传输到本地文件？

function downloadFileFromServer(url, fileName) {
  var xhr = new XMLHttpRequest();
  xhr.open('GET', url);
  xhr.responseType = 'blob';

  xhr.onreadystatechange = function() {
    if (xhr.readyState === 4) {
      if (xhr.status === 200) {
        var blob = xhr.response;
        var url = URL.createObjectURL(blob);

        var link = document.createElement('a');
        link.href = url;
        link.download = fileName;

        document.body.appendChild(link);
        link.click();
        document.body.removeChild(link);
      } else {
        console.error('Error: ' + xhr.status);
      }
    }
  };

  xhr.send();
}

// 使用示例
var serverUrl = 'http://example.com/download';
var localFileName = 'example.pdf';
downloadFileFromServer(serverUrl, localFileName);