How to use the fs.readdir function in fs

/* eslint-disable no-console */

const base64Img = require('base64-img');
const fs = require('fs');
const path = require('path');
const mkdirp = require('mkdirp');

const iconsSrcDir = path.join(__dirname, 'src', 'icons');
const iconsLibDir = path.join(__dirname, 'lib', 'icons');

mkdirp.sync(iconsLibDir);

fs.readdir(path.join(__dirname, 'src', 'icons'), (err, files) => {
  if (err) {
    console.error(err);
    process.exit(1);
  }
  for (const file of files) {
    base64Img.base64(path.join(iconsSrcDir, file), (err, data) => {
      if (err) {
        console.error(err);
        process.exit(1);
      }
      fs.writeFile(
        path.join(iconsLibDir, file + '.js'),
        `module.exports='${data}'`,
        err => {
          if (err) {
            console.error(err);

return new Promise((res, rej) => {
        fs.readdir(path, function(err, files){
            //err错误 , files 文件名列表包含文件夹与文件
            if(err){
                console.log('error:\n' + err);
                rej(-1)
                return;
            }
    
            files.forEach(function(file){
    
                fs.stat(path + '/' + file, function(err, stat){
                    if(err){console.log(err); return;}
                    if(stat.isDirectory()){			
                        // 如果是文件夹遍历
                        explorer(path + '/' + file);
                    }else{
                        // 读出所有的文件

exec(cmd, { timeout: _pdf2htmlEXTimeout }, (err, stdout, stderr) => {
    if (err) {
      log().error({ err, cmd, stdout, stderr }, 'Could not convert page to html');
      return callback({ code: 500, msg: 'Could not convert page to html' });
    }

    // Converting was succesful, get a list of files we generated
    fs.readdir(pagesDir, (err, files) => {
      if (err) {
        log().error(
          { err, contentId: ctx.contentId },
          'Could not read the %s directory to list the files',
          pagesDir
        );
        return callback({ code: 500, msg: 'Could not read the directory' });
      }

      // Only return the page HTML files, ie: page.i.html
      const htmlFiles = _.filter(files, file => {
        return file.split('.')[0] === 'page' && file.split('.').pop() === 'html';
      });

      // Add each HTML to the list of previews that should be stored.
      _.each(htmlFiles, htmlFile => {

fs.stat(filename, function (err, s) {
      if (!err && s.isDirectory()) {
        fs.readdir(filename, function(err, files) {
          if (err) {
            console.error('Error generating docs for files', filename, err);
            return cb(err);
          }
          files.forEach(function(file) {
            if (file.match(/\.js$/)) {
              oneFile(filename, file, cb), touched++;
            }
          });
          if(!touched) {
            cb();
          }
        });
      } else {
        cb();
      }

nThen((w) => {
        Fs.readdir(ctx.workdir, w((err, ret) => {
            if (err) { throw err; }
            files = ret.filter((f) => /^paylog_[0-9]+_[a-f0-9]+.bin$/.test(f));
        }));
    }).nThen((w) => {
        if (!files.length) { return; }

return (new Promise((fulfill, reject) => {
			fs.readdir(pathname, (err, files) => {
				if (err)
					reject(err);
				else
					fulfill(files);
			});
		}));
	}

function(cb) {
            fs.readdir(path, cb);
          },

return new Promise(function(resolve, reject) {
        fs.readdir(path, function(err, files) {
            err ? reject(err) : resolve(files)
        })
    })
}

function readdir(err) {
		if (err) 
			return cb(err);
		fs.readdir(path, function (err, ls) {
			if (err) 
				return cb (err);
			list = ls;
			shift();
		});
	}