in NodeJS, how do I use for loops to convert files to webp in mixed directories with fs and sharp?

Question

I'm trying to convert every item in a block of folders to webp, and convert everything in a the folders titled "thumbnail" to 300x300 and to webp.

The directories go like this

folder-one > subfolder-one > thumbnails  >   thumbnailone.jpg
                                             thumbnailtwo.jpg
                             imageone.jpg
                             imagetwo.jpg

             subfolder-two > thumbnails  >   thumbnailone.jpg
                                             thumbnailtwo.jpg
                             imageone.jpg
                             imagetwo.jpg

             subfolder-three > thumbnails  >   thumbnailone.jpg
                                             thumbnailtwo.jpg
                             imageone.jpg
                             imagetwo.jpg 

and there are 4 total folders.

Here's the code i've written. I'm not getting any error response but code is not working:(

const sharp = require('sharp');
const fs = require('fs')
const folders = ['folder-one','folder-two','folder-three','folder-four']
let i;
for (i = 0; i < folders.length; i++) {
  fs.readdirSync(`${fruits[i]}`, function(err, data){
    for (i = 0; i < data.length; i++) {
      fs.readdirSync(`/${data[i]}`, function read(err, data){
        for (i = 0; i < data.length; i++) {
          sharp(`${data[i]}.jpg`)
          .toFile(`${data[i]}.webp`, function(err) {
          });
        }
      })
      fs.readdirSync(`/${data[i]}/thumbnails`, function read(err, data){
        sharp(`${data[i]}.jpg`)
        .resize(300, 300)
        .toFile(`${data[i]}.webp`, function(err) {
        });
      })
    }
  })
}

Thank you!

Answer 1

You're using fs.readdirSync with the asynchronous callback style. Those should either be readdir s and you should check the errors, or not use the callback style. See the docs .

Here are some examples on how to do this with each of the options ( fs.readdir , fs.readdirSync , and fs.promises.readdir ):

// using readdir
fs.readdir(dir, function (err, data) {
  if (err) console.error(error)
  // do things with data
})

// using readdirSync
try {
  const data = fs.readdirSync(dir)
  // do things with data
} catch (err) {
  console.error(err)
}

// using the promisified version
const fs = require('fs/promises')
fs.readdir(dir)
  .then((data) => { /* do things with data */ })
  .catch((err) => { console.error(err) })
// or using async/await syntax
;(async () => {
  try {
    const  data = fs.readdir(dir)
    // do things with data
  } catch (err) {
    console.error(err)
  }
})