77535
Question:
I keep getting this error in this block of code below:
function openWebsocket(url) {
var ws;
ws = $websocket(url);
ws.onOpen(function(event) {
console.log(' Websocket connection established:', event);
});
ws.onMessage(function(message) {
var userObj = UserFactory.getUserObject();
var settings = userObj.alert_settings;
// The JSON parsing...
var parsedMsg = JSON.parse(message.data);
var alert = JSON.parse(parsedMsg);
var date = new Date(parseFloat(alert.start_epoch+'000'));
alert.hour = date.getHours() +':'+date.getMinutes();
alert.percent_change = Math.round(alert.percent_change);
var shouldPush = main_alert_filter(settings, alert);
updateFeed(alerts, shouldPush, alert);
});
}
I've looked at both <a href="https://stackoverflow.com/questions/15617164/parsing-json-giving-unexpected-token-o-error" rel="nofollow">Parsing JSON giving "unexpected token o" error</a> and <a href="https://stackoverflow.com/questions/8081701/i-keep-getting-uncaught-syntaxerror-unexpected-token-o" rel="nofollow">I keep getting "Uncaught SyntaxError: Unexpected token o"</a>
However neither answer helped. Because when I first run JSON.parse(message.data) I get a string back not an Object. So thus I have to run JSON.parse again to finally get a real object back.
<a href="https://i.stack.imgur.com/ef2gJ.png" rel="nofollow"><img alt="enter image description here" class="b-lazy" data-src="https://i.stack.imgur.com/ef2gJ.png" data-original="https://i.stack.imgur.com/ef2gJ.png" src="https://etrip.eimg.top/images/2019/05/07/timg.gif" /></a>
<strong>This is what message.data looks like:</strong>
"
"{\"term\": \"\\\"nike\\\"\", \"percent_change\": 125, \"hour\": \"10:9\", \"term_id\": 2890413, \"start_epoch\": 1420474140, \"term_trend_id\": 793950, \"end_epoch\": 1420477740, \"formatted_date_difference\": \"January 5, 2015\", \"tickers\": [\"NKE\", \"$PUM\", \"ADDYY\", \"LULU\", \"UA\", \"HIBB\"], \"twitter_preview\": \"\", \"type\": \"spike\", \"approved\": 1, \"search_preview\": [\"\"]}"
"
<strong>Now after the first parsing parsedMsg is a string that looks like this:</strong>
{"term": "minimum wage +increase", "percent_change": 729, "hour": "9:14", "term_id": 2522115, "start_epoch": 1447168440, "term_trend_id": 657898, "end_epoch": 1447175700, "formatted_date_difference": "November 10, 2015", "tickers": ["$JAB", "$SLCY", "AAL", "AAPL", "ABCD", "ABTL", "ADDYY", "ADM", "AEO", "AFCO", "AHC"......
<strong>Finally I need an actual object, so I have to run JSON.parse again to get this:</strong>
Object {term: "minimum wage +increase", percent_change: 729, hour: "9:14", term_id: 2522115, start_epoch: 1447168440…}
Another thing to note, I never get that error when I'm stepping through in Chrome. It only happens when I don't have the breakpoint set. Could this be a race condition type issue? Like it tries to JSON.parse something that isn't ready to be parsed?
<hr />UPDATE
Ok so sometimes the JSON is invalid apparently and sometimes not, so far I'm doing good without errors with the following snippet, thoughts?
if (typeof alert === 'object') {
// do nothing...
} else {
var alert = JSON.parse(alert);
}
Most of the time the alert result of JSON.parse(message.data) is a string so I need the other check to double parse it.
The JSON string you specified with message.data is not a well formed JSON parsed as String. It might be because the server is sending you a multi-part message during/after establishing the connection.
I suggest you print the message object received in OnMessage function and analyze if they are fully formed valid JSON Strings.
Why would you parse your json second time, its already been parsed in the first attempt.
Have a look at the <strong>snippet</strong>
<pre class="snippet-code-js lang-js prettyprint-override">var obj = "{\"term\": \"minimum wage +increase\", \"percent_change\": 729, \"hour\": \"9:14\", \"term_id\": 2522115, \"start_epoch\": 1447168440, \"term_trend_id\": 657898, \"end_epoch\": 1447175700, \"formatted_date_difference\": \"November 10, 2015\", \"tickers\": [\"$JAB\", \"$SLCY\", \"AAL\", \"AAPL\", \"ABCD\", \"ABTL\", \"ADDYY\"]}";
$(function(){
var data = JSON.parse(obj);
alert(typeof data);
console.log(data.tickers[0] +" -> an item in `tickers` array");
console.log(data.tickers);
});
<pre class="snippet-code-html lang-html prettyprint-override"><script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
Answer3:It looks like Your <strong>message.data</strong> is incomplete.
Take a look on the library docs You are using, maybe you should collect the data until it's end? Maybe there is some onEnd method?
