Batch rename file

//requiring path and fs modules
const path = require('path');
const fs = require('fs');
//joining path of directory
//get the files in current dir 
const directoryPath = path.join(__dirname, '');
//passsing directoryPath and callback function
var index=0; //file number counter
fs.readdir(directoryPath, function (err, files) {
    //handling error
    if (err) {
        return console.log('Unable to scan directory: ' + err);
    } 
    //listing all files using forEach
    files.forEach(function (file) {
        // Do whatever you want to do with the file
        console.log(file); 
        //rename the files
        if(file !='ren.js')
        {
        fs.renameSync(file, 'cover_'+index+'.jpg');
        index++;
        }       
    });
});