scanner.js

'use strict'
const fs = require('fs'),
      path = require('path')

exports.scan = function(folder) {
    if (!folder) return
    const stats = fs.statSync(folder)
    if (!stats.isDirectory()) throw new Error(`${folder} is not a directory`)
    
    const self = this
    const files = []
    let filesScanned = 0
    let bytesScanned = 0
    const startTime = Date.now()

    let wg = 0
    function d(p) {
        wg++
        fs.readdir(p, (err, entries) => {
            if (err) throw err
            for (const entry of entries) {
                const fullPath = path.join(p, entry)
                wg++
                fs.stat(fullPath, (err, stats) => {
                    if (err) throw err
                    if (stats.isDirectory()) {d(fullPath); done()}
                    else done(stats)
                })
            }
            done()
        })
    }
    function done(stats) {
        wg--
        if (stats) {
            filesScanned++
            bytesScanned += stats.size
        }
        if (!wg) {
            const timeTaken = Math.ceil((Date.now() - startTime)/1000)
            console.log(`Scanned ${filesScanned} files, ${bytesScanned} bytes in ${timeTaken} seconds`)
            return
        }
    }
    d(folder)
}