RunKit + npm: msgpack-js

let msgpack = require("msgpack-js") const message = [ 'ATcq1N', { type: 2, data: [ 'hi' ], nsp: '/' }, { except: [ 'qeoUFZeGyBlewzL_AAAA' ], rooms: undefined, flags: { broadcast: true } } ]; const copy_message = [ 'ATcq1N', { type: 2, data: [ 'hi' ], nsp: '/' }, { except: [ 'qeoUFZeGyBlewzL_AAAA' ], rooms: undefined, flags: { broadcast: true } } ]; let firstMessage = msgpack.encode(message) let secondMessage = msgpack.encode(copy_message) const modFirstMessage = firstMessage const modSecondMessage = secondMessage.toString() console.log(modFirstMessage.length) console.log(modSecondMessage.length) console.log(msgpack.decode(modFirstMessage)) console.log(msgpack.decode(modSecondMessage))