Avoid compressing image twice using imagemin

Question

I have several directories of images that I have compressed using Imagemin. I would like to add my script to my build so when new images are added they are automatically compressed. How would I go about checking if an image is already compressed so it does not get compressed again? The script is written purely in JS as of now using mozjpg plugin and pngquant.

I would like this to be as much of an automated solution as possible without having to delete old images or create new directories manually.

const imagemin = require('imagemin');
const imageminMozjpeg = require('imagemin-mozjpeg');
const imageminPngquant = require('imagemin-pngquant');


var images = ["15 directories"];

var i;
for (i = 0; i < 14; i++) {
  (async () => {
   const files = await imagemin([images[i]], {
    destination: images[i],
    plugins: [
        imageminMozjpeg({
          quality: 70,
        }),
    ]
   });

   console.log(files);
   //=> [{data: <Buffer 89 50 4e …>, path: 'build/images/foo.jpg'}, …]
  })();

  (async () => {
   const filesPNG = await imagemin([images[i]], {
    destination: images[i],
    plugins: [
        imageminPngquant({ quality: [0.6, 0.7] })
    ]
   });

   console.log(filesPNG);
   //=> [{data: <Buffer 89 50 4e …>, path: 'build/images/foo.jpg'}, …]
  })();
}