在承诺

Question

此处的函数会创建一堆文件，但不会写入它们。但是，如果我最后删除Promise.all并且根本不解决该功能，它会将数据写入文件。我尝试写的东西并不重要，我可以评论所有内容，然后写下“你好世界”。它仍然不会写任何东西。问题很简单，为什么？

const writeSmilFiles = (smilInfo) => {
  return new Promise ((resolve, reject) => {
    const p1 = smilPartOne();
    const p2 = smilPartTwo();

    let promises = dataTypes.new.camera_set.map(instance => {
      return new Promise((resolve, reject) => {
        const smilEntries = smilInfo.filter(smil => smil.BroadcastAndKlippTupleId == instance.BroadcastAndKlippTupleId && smil.CameraId == instance.CameraId);
        try {
          const fileName = `${__dirname}/newSmilFiles/${smilEntries[0].Smil}`;
          const file = fs.createWriteStream(fileName);
          file.write(p1);

          smilEntries.forEach(entry => {
            const smilEntry = smilSwitch(entry.Filename, entry.Bitrate, entry.Width, entry.Height);
            file.write(smilEntry);
            console.log(smilEntry);
            file.write('\n');
        });

          file.write(p2);
          file.end();
          resolve(`Smil written.`);
        } catch (ex) {
          reject(ex);
        }
      });
    });

    Promise.all(promises).then(msg => {
      resolve(msg);
    });
  });
};

Answer 1

当流实际完成时解析：

file.on("finish", () => resolve(`Smil written.`));