Parsing JSON under Array object

Question

I have a simple JSON string, encapsulated in an array created using JSONArray and JSONObject form org.json in Java.

var outObjA = [{"LoginTime":"2018-02-14 08:51:48.0","User":"f00dl3","RemoteIP":"127.0.0.1"}];

I am trying to parse this in JavaScript. First I iterate over the array encapsulating the data using an `i" counter:

for(var i = 0; i < outObjA.length; i++) { var jsonData = JSON.parse(outObjA[i]); console.log(jsonData); }

When I attempt to parse the JSON, I get an error:

SyntaxError: JSON.parse: unexpected character at line 1 column 2 of the JSON data

I built a try/catch into it and it returns an object:

for (var i = 0; i < outObjA.length; i++) { var jsonData = null; try { jsonData = JSON.parse(outObjA[i]); } catch (e) { jsonData = outObjA[i]; } console.log(jsonData); }

Returned:

{ "LoginTime": "2018-02-14 08:51:48.0", "User": "f00dl3", "RemoteIP": "127.0.0.1" }

This is valid JSON, is it not?

Thats not json... that's javascript object, you can't parse a JavaScript object, remove JSON.parse( — Liam
– Liam, Commented Feb 14, 2018 at 15:41
outObjA is already an object you don't have to parse it! If it was a string you'd have to. — Liora Haydont
– Liora Haydont, Commented Feb 14, 2018 at 15:42
stackoverflow.com/questions/8294088/javascript-object-vs-json — messerbill
– messerbill, Commented Feb 14, 2018 at 15:43
it's an object written in JavaScript Object Notation, but since it's already in Javascript it doesn't need to be parsed. — I wrestled a bear once.
– I wrestled a bear once., Commented Feb 14, 2018 at 15:44
@Occam'sRazor JSON cannot be an object, so to say it's an object written .... is confusing. JSON is a string (which I suppose is an object...), that represents an object — Liam
– Liam, Commented Feb 14, 2018 at 15:48

Racil Hilan · Accepted Answer · 2018-02-14 15:49:44Z

That's not a JSON string, it's a JavaScript array. To make it a JSON string, surround it with apostrophes, then you can parse it, and finally loop through it:

var outObjA = '[{"LoginTime":"2018-02-14 08:51:48.0","User":"f00dl3","RemoteIP":"127.0.0.1"}]'; var outObjA = JSON.parse(outObjA); for (var i = 0; i < outObjA.length; i++) { var jsonData = outObjA[i]; console.log(jsonData); }

Or better, you can loop through it directly without parsing:

var outObjA = [{"LoginTime": "2018-02-14 08:51:48.0", "User": "f00dl3", "RemoteIP": "127.0.0.1"}]; for (var i = 0; i < outObjA.length; i++) { var jsonData = outObjA[i]; console.log(jsonData); }

Liam · Accepted Answer · 2018-02-14 15:59:45Z

This line is not necessary.

 for(var i = 0; i < outObjA.length; i++) { var jsonData = JSON.parse(outObjA[i]); console.log(jsonData); }

Because outObjA is a array type not json,it does not need parsing simply retrieve it and display it.

The JSON.parse() method parses a JSON string, constructing the JavaScript value or object described by the string. An optional reviver function can be provided to perform a transformation on the resulting object before it is returned, source.

To expand further take this example from Mozilla ,

var json = '{"result":true, "count":42}';

The reason why this needs parsing is because its a string type, the JSON.parse converts that string into a JSON object, thus making it accessible. like this,

obj = JSON.parse(json); console.log(obj.count); // expected output: 42 console.log(obj.result); // expected output: tru

The only way your code would work is if you did this.

var outObjA = ['{"LoginTime":"2018-02-14 08:51:48.0","User":"f00dl3","RemoteIP":"127.0.0.1"}'];

This way the element at position zero is a string, not a JSON object.

To conclude, strings are not JSON.

JSON objects are surrounded by curly braces {}.
JSON objects are written in key/value pairs.
Keys must be strings, and values must be a valid JSON data type (string, number, object, array, boolean or null).
Keys and values are separated by a colon.
Each key/value pair is separated by a comma.

i100 · Accepted Answer · 2018-02-14 15:47:00Z

you do not need parse for it is already json

you might use instead

var jsonData = outObjA[i]; console.log(jsonData['User']); // or any other key

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