NodeJS Packet Function

function EncryptDecrypt(data) {
    let numArray = Buffer.from([ 250, 158, 179]);
    for (var i = 0; i < data.length; i++) {
        if (data[i] != numArray[i % numArray.length]) {
            data[i] = (data[i] ^ numArray[i % numArray.length]);
        }
    }
    return data;
}

function SendMessage(message, type=255, cmd=255){
    message = Buffer.from(message);
    let length = message.length;
    let bArray = Buffer.alloc(length + 3);
    bArray[0] = type;
    bArray[1] = cmd;
    message.copy(bArray, 2);
    EncryptDecrypt(bArray);
    bArray[length + 2] = 0;
    return bArray;
}