Full steps to create a password generator using Node.js

$ npm init 

$ npm i commander chalk clipboardy

// index.js
console.log(process.argv)

$ node index

$ node index generate

// index.js
const program = require('commander');
program.version('1.0.0').description('Simple password generator').parse()

const program = require('commander');

program.version('1.0.0').description('Simple password generator')
program.option('-l --length <number>', 'length of password').parse()
console.log(program.opts())

program.option('-l --length <number>', 'length of password', '8').parse()
console.log(program.opts())

program.option('-l --length <number>', 'length of password', '8')
.option('-s --save', 'save password to password.txt').parse()

.option('-nn --no-number', 'remove numbers').parse()

.option('-ns --no-symbols', 'remove symbols').parse()

// index.js
const program = require('commander');
const createPassword = require('./utils/createPassword')
const log = console.log

program.version('1.0.0').description('Simple password generator')
program
.option('-l --length <number>', 'length of password', '8')
.option('-s --save', 'save password to password.txt')
.option('-nn --no-numbers', 'remove numbers')
.option('-ns --no-symbols', 'remove symbols').parse()

const {length, save, numbers, symbols} = program.opts()

// Get generated password
const generatedPassword = createPassword(length, numbers, symbols)

// Output generated password

log(generatedPassword)

// createPassword.js
const alpha = 'qwertyuiopasdfghjklzxcvbnm'
const numbers = '0123456789'
const symbols = '!@#$%^&*_-=+'


const createPassword = (length = 8, hasNumbers = true, hasSymbols = true) => {
    let chars = alpha
    hasNumbers ? (chars += numbers): ''
    hasSymbols ? (chars += symbols): ''
    return generatePassword(length, chars)
}

const generatePassword = (length, chars) => {
    let password = ''
    for(let i = 0; i < length; i++){
        password+= chars.charAt(Math.floor(Math.random()*chars.length))
    }
    return password
}
module.exports = createPassword

// index.js
const chalk = require('chalk');
log(chalk.blue('Generated Password: ') + chalk.bold(generatedPassword))

// index.js
const clipboardy = require('clipboardy');
// Copy to clipboardy
clipboardy.writeSync(generatedPassword)
log(chalk.yellow('Password copied to clipboardy!'))

// index.js
const savePassword = require('./utils/savePassword')
// Save to file
if (save) savePassword(generatedPassword)

const fs = require('fs')
const path = require('path')
const os = require('os')
const chalk = require('chalk')

const savePassword = (password) => {
    fs.open(path.join(__dirname, '../', 'passwords.txt'), 'a', '666', (e, id) => {
        fs.write(id, password + os.EOL, null, 'utf-8', ()=>{
            fs.close(id, ()=>{
                console.log(chalk.green('Password saved to passwords.txt'))
            })
        })
    })
}

module.exports = savePassword

// package.json
  "preferGlobal": true,
  "bin":"./index.js",

//index.js
#!/usr/bin/env node //Add the first line