Develop Reference

Node-Red: Parse JavaScript Object with Double value

I am using node-RED to call in data from a robot. In the debug window it says it is a 'msg: Object', and when I copy it to a notepad it takes the format: {"topic":"","payload":27.659992218017578,"_session":{"type":"tcp","id":"0151ff7339437ec6"},"_msgid":"6a6897605a523366"}
I am also not sure if this is a JSON object or not, as I see examples with '' around the brackets.
I am trying to use the function node within node-red to parse this to attain the "payload" value. However, it keeps returning as undefined.
I am using the script:
var json =msg.payload;
var obj = JSON.parse(json);
msg.payload = console.log(obj.payload);
return msg;
I am a beginner to javascript and JSON, however I have tried searching and all examples only have integers as the parsing value. I am also unsure if the value name itself 'payload' is causing an issue. I have also attempted to stringify and using 'getDouble' but had no luck, which I owe to my lack of experience.
I appreciate any guidance.

You don't need to do anything. The value of msg.payload is already a double.
Without a lot more context of what you are trying to do there isn't anything else that we can say here.

After the node that gets the above information (the data in {} in the question}, I then used the function node to construct the message that I wanted to sent to the IIOT platform. I did
const str = msg.payload
msg.payload = " ," + str
// where the text I required was in " "
return msg
Also this works:
msg.payload = "," + msg.payload
return msg
And then I used the MQTT output node to publish this to the IIOT platform

Creating object from JSON and parsing JSON - different results

I am trying to use JQuery to parse some JSON being sent back from an AJAX call. It appears to be failing to parse, and JSLint also says it's invalid JSON.
However, if I create the object directly, it works and I am able to loop through it - please see below:
var json = {layers:[{layer1:[17,16,15,14,12]}]}
alert(json)// <- This works and output object Object
var somestring = "{layers:[{layer1:[17,16,15,14,12]}]}"
var parsing = JSON.parse(somestring)
alert(parsing) // <- this doesn't and breaks on parse
// The below code will work provided the parsing is commented out
json.layers.forEach(function (outerObj)
{
Object.keys(outerObj).forEach(function (key)
{
outerObj[key].forEach(function (item)
{
alert(item)
});
});
});
I'm struggling to wrap my head around why it won't parse, but appears to work.
Edit
I realise by wrapping quotes around layers and layer1 fixes it, just not sure why it works one way - but not the other.

there is a difference between javascript object and JSON object, all keys of JSON object must be quoted.
var somestring = "{layers:[{layer1:[17,16,15,14,12]}]}"// not a valid json to parse, it is a normal string, you can use JSON.stringify() to make it a valid json identifiable string.
so the correct JSON string will look like
var somestring = '{"layers":[{"layer1":[17,16,15,14,12]}]}';
var parsedJson = JSON.parse(somestring)

If you change sometring to some of the following examples, it will works.
var somestring = '{"layers":[{"layer1":[17,16,15,14,12]}]}'
var somestring = "{\"layers\":[{\"layer1\":[17,16,15,14,12]}]}"
The reason for this is, basically, that's how JSON was specified.
For further examples, take a look at w3schools

Best practice is to use JSON.stringify(Object) on one side, and JSON.parse(String) on the other. This will save you many hours of scratching your head over some niggling detail.
In your example, you could resolve the problem by
var somestring = JSON.stringify(json)
For future reference, however, JSON keys must be quoted, so your somestring should be written as:
var somestring = '{"layers":[{"layer1":[17,16,15,14,12]}]}'
Good luck!

JSON.parse() returns wrong values for integers

[EDIT] I was modyfing the data later and it was reflected in the object when expanding it, I will accept my answer when I can.[/EDIT]
I've got a simple JSON string that needs parsing:
{"Points": [{"x": 0,"y": 33},{"x": 2200,"y": 28},{"x": 4400,"y": 23},{"x": 6600,"y": 20},{"x": 8800,"y": 19},{"x": 11000,"y": 18},{"x": 13200,"y": 17},{"x": 15400,"y": 15},{"x": 17600,"y": 13},{"x": 19800,"y": 12}]}
The string is generated by C++ code for graph drawing purposes. When I paste it into a json formatter it parses fine, giving proper values. The problem I'm facing are wierd Y values, for example the first object in array "Points" has y value of 20 - and there are no 20's anywhere in the string.
See attached picture, it explains everything. The code before what's on the picture is as follows:
RequestJSONParse: function(Data)
{
var Request = Data.split("|");
var RequestType = Request[0];
var RequestParams = Request[1];
var RequestData = undefined;
if (typeof Request[2] != "undefined" && Request[2] != "")
{
console.log("---");
console.log(Request[2]);
console.log("---");
RequestData = JSON.parse(Request[2]);
console.log("---");
console.log(RequestData);
console.log("---");
}
My question is - are the some special characters or a special way JSON.parse parses specifically x,y values? Or is this an encoding issue or something I can't even think of? I've been on this project for 2 years and didn't ever encounter anything like this and most of our UI is made by parsing JSON data.
Image explaining the problem

Check here your do like this
var json = "{\"Points\": [{\"x\": 0,\"y\": 33},{\"x\": 2200,\"y\": 28},{\"x\": 4400,\"y\": 23},{\"x\": 6600,\"y\": 20},{\"x\": 8800,\"y\": 19},{\"x\": 11000,\"y\": 18},{\"x\": 13200,\"y\": 17},{\"x\": 15400,\"y\": 15},{\"x\": 17600,\"y\": 13},{\"x\": 19800,\"y\": 12}]}";
var Request = json.split("|");
var data = JSON.parse(Request[0]);
console.log(data);
U can use above code if u r getting string in this way....

#JamesThorpe Was on point, I was modifying the object later and my changes were reflected in the object when it was expanded. The blue i symbol was the missing link for me.

JSON.Parse,'Uncaught SyntaxError: Unexpected token o [duplicate]

This question already has answers here:
I keep getting "Uncaught SyntaxError: Unexpected token o"
(9 answers)
Closed 6 years ago.
I am having trouble with JSON returned from a web service. It looks like the JSON lacks quotes, but when I add quotes to the JSON, I get an error. Here is the error message: 'Uncaught SyntaxError: Unexpected token o. When I log the string to console:[object Object],[object Object]
Here is some example code that simulates the error:
//Error I am trying to solve
var jsonString = '[{"Id":"10","Name":"Matt"},{"Id":"1","Name":"Rock"}]';
var myData = JSON.parse(jsonString);
$(document).ready(function() {
var $grouplist = $('#groups');
$.each(myData, function() {
$('<li>' + this.Name + '</li>').appendTo($grouplist);
});
});
Here is the same code with the single quotes around the string. It works
//Successful Javascript
var jsonString = '[{"Id":"10","Name":"Matt"},{"Id":"1","Name":"Rock"}]';
var myData = JSON.parse(jsonString);
$(document).ready(function() {
var $grouplist = $('#groups');
$.each(myData, function() {
$('<li>' + this.Name + '</li>').appendTo($grouplist);
});
});
//Successful HTML
<ul id="groups"></ul>
But when I try to add quotes to the string, like I seem to need to in my real code, it fails:
//Does not work when I need to append quotes to the string:
var jsonStringNoQuotes = [{"Id":"10","Name":"Matt"},{"Id":"1","Name":"Rock"}];
jsonStringQuotes = "'" + jsonStringNoQuotes + "'";
var myData = JSON.parse(jsonStringQuotes);
$(document).ready(function() {
var $grouplist = $('#groups');
$.each(myData, function() {
$('<li>' + this.Name + ',' + this.Id + '</li>').appendTo($grouplist);
});
});
Here is the error:
log string to console:[object Object],[object Object]
data.js:809 Uncaught SyntaxError: Unexpected token '
I'm stumped. Any help appreciated! Thank you!

Without single quotes around it, you are creating an array with two objects inside of it. This is JavaScript's own syntax. When you add the quotes, that object (array+2 objects) is now a string. You can use JSON.parse to convert a string into a JavaScript object. You cannot use JSON.parse to convert a JavaScript object into a JavaScript object.
//String - you can use JSON.parse on it
var jsonStringNoQuotes = '[{"Id":"10","Name":"Matt"},{"Id":"1","Name":"Rock"}]';
//Already a javascript object - you cannot use JSON.parse on it
var jsonStringNoQuotes = [{"Id":"10","Name":"Matt"},{"Id":"1","Name":"Rock"}];
Furthermore, your last example fails because you are adding literal single quote characters to the JSON string. This is illegal. JSON specification states that only double quotes are allowed. If you were to console.log the following...
console.log("'"+[{"Id":"10","Name":"Matt"},{"Id":"1","Name":"Rock"}]+"'");
//Logs:
'[object Object],[object Object]'
You would see that it returns the string representation of the array, which gets converted to a comma separated list, and each list item would be the string representation of an object, which is [object Object]. Remember, associative arrays in javascript are simply objects with each key/value pair being a property/value.
Why does this happen? Because you are starting with a string "'", then you are trying to append the array to it, which requests the string representation of it, then you are appending another string "'".
Please do not confuse JSON with Javascript, as they are entirely different things. JSON is a data format that is humanly readable, and was intended to match the syntax used when creating javascript objects. JSON is a string. Javascript objects are not, and therefor when declared in code are not surrounded in quotes.
See this fiddle:
http://jsfiddle.net/NrnK5/

var jsonStringNoQuotes = [{"Id":"10","Name":"Matt"},{"Id":"1","Name":"Rock"}];
it will create json object. no need to parse.
jsonStringQuotes = "'" + jsonStringNoQuotes + "'";
will return '[object]'
thats why it(below) is causing error
var myData = JSON.parse(jsonStringQuotes);

Your last example is invalid JSON. Single quotes are not allowed in JSON except inside strings. In the second example, the single quotes are not in the string, but serve to show the start and end.
See http://www.json.org/ for the specifications.
Should add: Why do you think this: "like I seem to need to in my real code"? Then maybe we can help you come up with the solution.

Maybe what comes from the server is already evaluated as JSON object? For example, using jQuery get method:
$.get('/service', function(data) {
var obj = data;
/*
"obj" is evaluated at this point if server responded
with "application/json" or similar.
*/
for (var i = 0; i < obj.length; i++) {
console.log(obj[i].Name);
}
});
Alternatively, if you need to turn JSON object into JSON string literal, you can use JSON.stringify:
var json = [{"Id":"10","Name":"Matt"},{"Id":"1","Name":"Rock"}];
var jsonString = JSON.stringify(json);
But in this case I don't understand why you can't just take the json variable and refer to it instead of stringifying and parsing.

Parsing malformed JSON with Javascript

I want to parse this content using Javascript. The data looks like this:
{"ss":[["Thu","7:00","Final",,"BAL","19","ATL","20",,,"56808",,"PRE4","2015"],["Thu","7:00","Final",,"NO","10","GB","38",,,"56809",,"PRE4","2015"]]}
Every single tutorial online teaches you how to parse JSON using Twitter, but I am not quite sure how parsing with JSON works.
I would like to set this up on a website to view the NFL team scores for a fun project and a good learning experience about parsing JSON, as I could care less about Twitter stuff.
Is this possible? Any good tutorials to start with? Even some starting code?

Generally speaking, you can use JSON.parse to do this. However, that snippet that you have does not appear to be strictly valid JSON (as seen here: http://jsfiddle.net/yK3Gf/ and also by validating the source JSON here: http://jsonlint.com/).
So you will either need to parse it by hand, or get nfl.com to fix up their JSON.
As an alternative, their JSON does parse successfully when using eval(), so you could parse it with something like:
var parsedData = eval('(' + jsonData + ')');
...as shown here: http://jsfiddle.net/yK3Gf/1/
Though be aware that parsing JSON in this way is generally frowned upon (particularly when the data being parsed is being delivered by a third-party source), as it leaves you open to XSS attacks should the data happen to include any executable code inside of it.

I am in a similar position - non javascript expert working on a fun project to familiarize myself with javascript, ajax, and json.
I took three different steps to handle the problem. I welcome any feedback on improving the solution.
The first step is to query the nfl site to pull down the scores. Because the source of the json, the nfl site, is different from your site, you will have to work around the javascript security constraints against cross domain querying. I found this stackoverflow link to be a good reference. I used JSONP for the workaround. I used http://whateverorigin.org/ as the indirection site.
$.getJSON('http://whateverorigin.org/get?url=' + encodeURIComponent('http://www.nfl.com/liveupdate/scorestrip/scorestrip.json') + '&callback=?', handleQueryForScoresResult);
As others have pointed out, the nfl site returns invalid json data. The following sample line illustrates the problem:
["Sun","4:25","Final",,"TEN","7","MIN","30",,,"55571",,"REG5","2012"],
Notice the empty array element values (the repeated commas with no data in between). So in my json callback function, I corrected the data by adding empty strings (two double quotes) to repeated commas before calling jquery to parse the json data:
function handleQueryForScoresResult(data) {
var jsonStr = data.contents;
jsonStr = jsonStr.replace(/,,/g, ',"",');
jsonStr = jsonStr.replace(/,,/g, ',"",');
var scoresData = jQuery.parseJSON(jsonStr).ss;
.
.
.
}
Lastly, I created GameScores object to encapsulate the json data.
function GameScore(scoreData) {
this.scoreData = scoreData;
scoreData[2] = scoreData[2].toLowerCase();
scoreData[5] = parseInt(scoreData[5]);
scoreData[7] = parseInt(scoreData[7]);
}
function GameScore_getAwayTeam() { return this.scoreData[4]; }
function GameScore_getHomeTeam() { return this.scoreData[6]; }
function GameScore_isFinal() { return this.scoreData[2]=="final"; }
function GameScore_getHomeTeamScore() { return this.scoreData[7]; }
function GameScore_getAwayTeamScore() { return this.scoreData[5]; }
function GameScore_doesHomeTeamLead() { return this.scoreData[7]> this.scoreData[5]; }
function GameScore_doesAwayTeamLead() { return this.scoreData[5]> this.scoreData[7]; }
function GameScore_getWeekId() { return this.scoreData[12]; }
GameScore.prototype.getHomeTeam = GameScore_getHomeTeam;
GameScore.prototype.getAwayTeam = GameScore_getAwayTeam;
GameScore.prototype.isFinal = GameScore_isFinal;
GameScore.prototype.getHomeTeamScore = GameScore_getHomeTeamScore;
GameScore.prototype.getAwayTeamScore = GameScore_getAwayTeamScore;
GameScore.prototype.doesHomeTeamLead = GameScore_doesHomeTeamLead;
GameScore.prototype.doesAwayTeamLead = GameScore_doesAwayTeamLead;
GameScore.prototype.getWeekId = GameScore_getWeekId;
I only added a few accessors as I did not need most of the data. Your needs may vary.

We are using mootools for stuff like that, but you can do it it plain JavaScript as well: http://www.json.org/js.html.

Let's assume you already have a valid JSON String (jsonString) to parse. (If you don't know how to retrieve a String to parse using XMLHttpRequest from the given url you will have to look into that first.)
With plain JavaScript you will have to add Douglas Crockford's JSON library (or something similar) in order to provide a parsing Function if there is no native implementation:
var json = json_parse(jsonString) ;
link
With a JavaScript library like jQuery this would be
var json = $.parseJSON(jsonString) ;
Now, traversing the resultant JSON Object is a whole other issue, because you will have to know its structure before you can retrieve specific data.
In this particular case -- if it was indeed well formed -- you would have to do the following:
var data = json.ss ;
for(var i = 0 ; i < data.length ; i++) {
var entry = data[i] ;
var day = entry[0] ; //!! the Arrays seem to have a format where the first entry always contains the data and so forth...
/* ... */
// then do something with the data bits
}

Your main problem is that fact that the JSON your pulling in is malformed or not valid according to RFC 4627.
What you can do is grab the copy the JSON data and format it using this tool http://www.freeformatter.com/json-formatter.html
After you have the formatted version then you can use the jQuery ajax call
$.ajax({
url: "your-formatted.json",
dataType: 'json',
success: function (data) {
for (var i = 0; i < data.ss.length; i++) {
document.write("Day: " + data.ss[i][0]);
document.write("<br/>");
document.write("Time: " + data.ss[i][1]);
document.write("<br/><br/>");
}
}
});
You shouldn't actually use document.write in your application. This is only for example purpose of displaying the data.

For this specific issue (the empty indexes within the arrays from the JSON response) I did a regex replacement with a lookahead assertion. Considering that request contains the XMLHttpRequest:
request.responseText.replace(/,(?=,)/gm, ",\"\"")
This will turn ,, into ,"", and will also work in case there are more commas in sequence, so ,,, becomes ,"","",. You can use JSON.parse() afterwards.

This malformed JSON can be parsed by the dirty-json NPM package (I am the author).
You can test a demo of the parser here: https://rmarcus.info/dirty-json
The parser interprets the JSON in your original question as equivalent to the following valid JSON:
{
"ss": [
[
"Thu",
"7:00",
"Final",
"BAL",
"19",
"ATL",
"20",
"56808",
"PRE4",
"2015"
],
[
"Thu",
"7:00",
"Final",
"NO",
"10",
"GB",
"38",
"56809",
"PRE4",
"2015"
]
]
}