Generate a JWT using javascript

generate_jwt.js

const crypto = require('crypto')
# header
const header = { "alg": "HS256", "typ": "JWT" }
const encodedHeader = Buffer.from(JSON.stringify(header)).toString('base64')
# payload
const payload = { username: 'Flavio' }
const encodedPayload = Buffer.from(JSON.stringify(payload)).toString('base64')
# signature
const jwtSecret = 'secretKey'
const signature = crypto.createHmac('sha256', jwtSecret).update(encodedHeader + '.' + encodedPayload).digest('base64')

const jwt = `${encodedHeader}.${encodedPayload}.${signature}`