WebSocket.binaryType

var binaryType = aWebSocket.binaryType;

// Create WebSocket connection.
const socket = new WebSocket("ws://localhost:8080");
// Change binary type from "blob" to "arraybuffer"
socket.binaryType = "arraybuffer";

// Listen for messages
socket.addEventListener("message", function (event) {
    if(event.data instanceof ArrayBuffer) {
        // binary frame
        const view = new DataView(event.data);
        console.log(view.getInt32(0));
    } else {
        // text frame
        console.log(event.data);
    }
});