小编pom*_*pon的帖子

我重构了一个使用promises的简单实用程序.它从Web获取pdf并将其保存到磁盘.然后它应该保存到磁盘后在pdf查看器中打开文件.该文件出现在磁盘上并且有效,shell命令打开OSX预览应用程序,但会弹出一个对话框,抱怨该文件为空.

将文件流写入磁盘后,执行shell函数的最佳方法是什么？

// download a pdf and save to disk
// open pdf in osx preview for example
download_pdf()
  .then(function(path) {
    shell.exec('open ' + path).code !== 0);
  });

function download_pdf() {
  const path = '/local/some.pdf';
  const url = 'http://somewebsite/some.pdf';
  const stream = request(url);
  const write = stream.pipe(fs.createWriteStream(path))
  return streamToPromise(stream);
}

function streamToPromise(stream) {
  return new Promise(function(resolve, reject) {
    // resolve with location of saved file
    stream.on("end", resolve(stream.dests[0].path));
    stream.on("error", reject);
  })
}