Using Promise.all with loops-CodePudding

In my code, I want to compare arrays and delete files on the server that do not match in arrays. Since unlink is an asynchronous operation, I decided to use the async await. But I'm not sure if I did everything right. Do I need to wrap everything in the Promise.all or remove it altogether

oldFiles.map(async (oldFile) => {
  await Promise.all(
    editedFiles.map(async (editedFile, index) => {
      if (oldFile === editedFile) {
        return;
      }
      //delete file if it the last editedFile that has no overlap with oldFile
      if (index === editedFiles.length - 1) {
        await unlink(`${filesDir}/${oldFile}`);
      }
    })
  );
});

CodePudding user response：

I feel like a better solution would be to filter oldFiles for any editedFiles then create an array of unlink promises to wait on

const editedFilesHash = new Set(editedFiles); // makes for faster lookups

await Promise.all(
  oldFiles
    .filter((oldFile) => !editedFilesHash.has(oldFile))
    .map((oldFile) => unlink(`${filesDir}/${oldFile}`))
);

It was totally unclear what the last index check was for and it seemed completely unnecessary to the overall logic.