Server cannot receives Uint8Array from client, it only receives a plain Object

[Meigyoku-Thmn]

You want to:

• report a bug
• request a feature

Current behaviour

Server cannot receives Uint8Array from client, it only receives a plain Object.

Steps to reproduce (if the current behaviour is a bug)

Client side:

let binary = new Uint8Array(5);
binary.fill(12);
socket.emit('binary', binary);

Server side:

socket.on('binary', (binaryData) => {
   console.log(binaryData);
});

Result of console.log on Server side:

{ '0': 12,
  '1': 12,
  '2': 12,
  '3': 12,
  '4': 12,
  '5': 12 }

Expected behaviour

Server side receives a Buffer, an ArrayBuffer, or Uint8Array.

Setup

• OS: Windows 10
• browser: Google Chrome and Mozilla Firefox, Nodejs v8.9.1
• socket.io version: 2.0.4

Other information (e.g. stacktraces, related issues, suggestions how to fix)

I don't know if this is a bug or not.
Edit: Reason to do this: to save bandwidth.

[byrgazov]

let binary = new Uint8Array(5);
binary.fill(12);
let buffer = binary.buffer.slice(binary.byteOffset, binary.byteOffset + binary.byteLength);
socket.emit('binary', buffer);

const toArrayBuffer = require('to-arraybuffer');

let binary = new Uint8Array(5);
binary.fill(12);
let buffer = toArrayBuffer(binary);
socket.emit('binary', buffer);

[darrachequesne]

This was fixed by socketio/socket.io-parser@8822578, included in socket.io-parser@3.1.3 & socket.io@2.0.4.

[cdauth]

I ended up here while searching whether/how it is possible to send Uint8Arrays over Socket.IO. For anyone coming here for the same issue, be informed that you can send an Uint8Array over a Socket.IO socket, but it will arrive as an ArrayBuffer. To convert it back, you have to wrap it by doing new Uint8Array(arrayBuffer).