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I’m getting an error from websockets/ws:
/root/diag/node_modules/ws/lib/WebSocket.js:422
event.target = target;
^
TypeError: Cannot assign to read only property 'target' of reserved fields (2, 3) must be empty
at WebSocket.onError (/root/diag/node_modules/ws/lib/WebSocket.js:422:18)
at WebSocket.emit (events.js:110:17)
at Receiver.onerror (/root/diag/node_modules/ws/lib/WebSocket.js:832:10)
at Receiver.error (/root/diag/node_modules/ws/lib/Receiver.js:317:8)
at Receiver.processPacket (/root/diag/node_modules/ws/lib/Receiver.js:186:12)
at Receiver.add (/root/diag/node_modules/ws/lib/Receiver.js:91:24)
at firstHandler (/root/diag/node_modules/ws/lib/WebSocket.js:767:22)
at process._tickCallback (node.js:355:11)
This is not referring to any specific line in my code, so I don’t even know where in my code is causing this.
Is this a bug with the new update of module or am I doing something wrong?
I haven’t updated the websocket client (which is where the error is coming from) in a while.
EDIT
The websocket is used at two different locations:
// main file that then passes socket to libdiag.js
socket.on('connect', function () {
socket.emit('authenticate', {
method: 'token',
credentials: token
});
});
socket.on('authenticate', function(packet) {
var data = JSON.parse(packet.data);
if (packet.channel == CHANNEL && data.status == "authenticated") {
libdiag.start(socket, CHANNEL);
}
});
socket.on('disconnect', function () {
start();
});
socket.on('error', function (err) {
libdiag.error(err); // This is just a logger that writes to file
});
And this file
// This is libdiag.js
socket.on('data', function (packet) {
var data = JSON.parse(packet.data);
// New listener is requesting handshake
if (packet.type == SOCKET_HANDSHAKE) {
_handshake(data);
}
// A listener has left
if (packet.type == SOCKET_CLOSED) {
_listenerLeft(data);
}
if (packet.type == SOCKET_UPDATE) {
_read(data);
}
});
socket.on('disconnect', function () {
libdiag.destroy(); // This calls socket.disconnect() and sets the variables to null
});
Answer
I believe you are trying to bind a DOM Level 2 to one of your websockets callbacks, DOM Level 2 Events have their target property set as readOnly:
// Introduced in DOM Level 2:
interface Event {
// PhaseType
const unsigned short CAPTURING_PHASE = 1;
const unsigned short AT_TARGET = 2;
const unsigned short BUBBLING_PHASE = 3;
readonly attribute DOMString type;
readonly attribute EventTarget target;
readonly attribute EventTarget currentTarget;
readonly attribute unsigned short eventPhase;
readonly attribute boolean bubbles;
readonly attribute boolean cancelable;
readonly attribute DOMTimeStamp timeStamp;
void stopPropagation();
void preventDefault();
void initEvent(in DOMString eventTypeArg,
in boolean canBubbleArg,
in boolean cancelableArg);
};
And it seems that in your flow, something is triggering the onError handler of the websocket, which tries to change the event.target:
function onError (event) {
event.type = 'error';
event.target = target;
listener.call(target, event);
}
I believe this is the root cause of the error you are seeing there in your console. It would be helpful if you show us the code regarding on the events/callbacks/handlers you are binding or using with your websocket in order to determine a way to not use a DOM Level 2 event.