WebSocket JSON javascript/jquery

Question

I'm sending JSON via a websocket, but some of the created messages are empty.

function chVol(vol){
 var send = {};
 send["payload"] = {};
 send["payload"]["volume"] = vol;
 ws.send(JSON.stringify(send));
}

If vol has the value 0 or 1, the messages are correct and at some other values of vol, too. I'm changing vol with a slider and when I'm logging JSON.stringify(send) all messages are correct, but not when

ws.onmessage = function (e) {
            data = JSON.parse(e.data);
            console.log(data);
};

is called. Any ideas what is going on here?

It's not clear what you're asking. onmessage is for incoming messages, it won't log outgoing messages you sent using .send(). Is that the confusion? — ydaniv
– ydaniv, Commented Oct 14, 2015 at 6:31

user229044 · Accepted Answer · 2015-10-13 13:28:04Z

2

You can't do this:

var send = {};
send["payload"]["volume"] = vol;

That will cause an exception, as you're attempting to access the property 'volume' on undefined.

You need to first initialize send['payload'] to an empty object:

var send = {}
send['payload'] = {}
send['payload']['volume'] = vol

answered Oct 13, 2015 at 13:28

user229044♦

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3 Comments

Rory McCrossan Over a year ago

Or you could make the definition in to a single object declaration: var send = { payload: { volume: vol } }; +1 for fixing the problem regardless.

Johannes Gi Over a year ago

i didn't copy the whole code, because there a much more parameters that I submit. send["payload"] = {}; is in the code before...

user229044 Over a year ago

@JohannesGi then please update your question and include code that actually works. It's important to include a minimal complete example, otherwise we cannot help you.

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