I would like to resize and transform an image before adding to formData. I just tested a lot with e.g. the sharp library but I can't find a solution.

Some code:

formData.append('attachment', fs.createReadStream('sky.jpeg')); //This works fine

The formData accepts only JPEG, so if the user choose a png it should be transformed.

I tried this:

const trans = await sharp('png.png')
      .resize(1024)
      .toFormat("jpeg", { mozjpeg: true })

But the output is not be able to add to formData e.g.

formData.append('attachment', trans);