Get files in a dir by ext.

traverseFile.js

const fs = require('node:fs')
const path = require('node:path')

/**
 * Traverse files in a dir
 * @param {string} dirPath Dir path
 * @param {string[]} ext
 * @param {number} [deep]
 * @param {any[]} [collection]
 */
function traverseFile(dirPath, ext, deep = Infinity, collection = []) {
  if (deep <= 0) return collection

  const pathArr = fs.readdirSync(dirPath)

  pathArr.forEach((itemName) => {
    const currentItemPath = path.resolve(dirPath, itemName)
    const currentItemStat = fs.statSync(currentItemPath)

    if (currentItemStat.isDirectory()) {
      traverseFile(currentItemPath, ext, deep - 1, collection)
    } else {
      const itemExt = path.extname(itemName)

      ext.includes(itemExt) &&
        collection.push({
          path: path.resolve(__dirname, itemName),
          name: itemName,
          ext: itemExt,
        })
    }
  })

  return collection
}

console.log(traverseFile(path.resolve(__dirname, '../percs/data'), ['.md', '.mdx']))