https://www.xgeek.net/node-js/encrypte-decrypte-string-in-node-js/

crypto.js

var crypto = require("crypto");
var uncipheredText = 'password123';
var secretkey ='your_secret_key';

var cipher = crypto.createCipheriv('rc4', secretkey , '');
var crypt = cipher.update(uncipheredText, 'utf8', 'base64');
crypt += cipher.final('base64');
console.log('Encrypted String :' + crypt );

var decipher = crypto.createDecipheriv('rc4',secretkey , '');
var data = decipher.update(crypt, 'base64', 'utf8');
data += decipher.final('utf8');

console.log('Decrypted String :' + data);