Get values from JSON using javascript

Question

I need to get values from a JSONString using javaScript. I did the following :

jsonData = JSON.stringify(data);
var jsonVar = "jVar";


for (var l = 0; l < jsonData.jsonVar.length; l++) {
                    var item = jsonData.itemI+"-"+itemJ+"-"+itemK.split(' ').join('')[i];
                    alert(cuecard);
                }

Here is the JSONData:

{"jVar":["123","234"]}

But i am getting the following exception:

Uncaught TypeError: Cannot read property 'length' of undefined
at Object.success (test.jsp:62)
at i (jquery.min.js:2)
at Object.fireWith [as resolveWith] (jquery.min.js:2)
at A (jquery.min.js:4)
at XMLHttpRequest.<anonymous> (jquery.min.js:4)

I saw the example in here and i dont know the mistake i am doing.Can any one please suggest.

`JSON.stringify` if for converting a value into a JSON string. If you want to parse a JSON string, use `JSON.parse()`. — JLRishe, Sep 27 '17 at 15:53
Possible duplicate of [Parse JSON in JavaScript?](https://stackoverflow.com/questions/4935632/parse-json-in-javascript) — Dima Kozhevin, Sep 27 '17 at 15:54
What are you trying to do with that 'itemI', 'itemJ', and 'itemK' stuff? That doesn't resemble your data at all. — Daniel Beck, Sep 27 '17 at 15:57

Jamiec · Answer 1 · 2017-09-27T16:00:16.463

2

You have it the wrong way round - JSON.stringify turns a javascript object to a string. And JSON.parse parses a JSON String to a javascript object.

Also, having done that, if you want to read a property using a string use square bracket notation:

var jsonData = JSON.parse(data);
var jsonVar = "jVar";

for (var l = 0; l < jsonData[jsonVar].length; l++) {
  var arrayItem = jsonData[jsonVar][l];
 ...
}

(As an aside l is a bad choice for a loop control variable - looks too much like a 1)

edited Sep 27 '17 at 16:00

answered Sep 27 '17 at 15:53

Jamiec

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It still has another issue with the property accessor. – epascarello Sep 27 '17 at 15:54
@epascarello yes, I saw that too. Updated answer – Jamiec Sep 27 '17 at 15:55

Himan · Answer 2 · 2017-09-27T15:55:57.657

0

You have to access the proprty like this.

for (var l = 0; l < jsonData[jVar].length; l++) {

}

edited Sep 27 '17 at 15:55

answered Sep 27 '17 at 15:54

Himan

379
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7

Still has another issue with the first line of the OPs code – epascarello Sep 27 '17 at 15:54
Yeah is see there are other issues. e.g "jsonData.itemI" itmel is not defined anywhere – Himan Sep 27 '17 at 15:57

score 0 · Answer 3 · answered Sep 27 '17 at 15:55

Make sure you have a valid JSON object first. I don't think what you have is valid to start with.

JSON.parse(yourValidJsonObject);

The above should give you a plain Javascript object you can work with.

Whereas, JSON.stringify(yourPlainJavascriptObject) will turn the plain js object to a JSON object.

score -1 · Answer 4 · answered Sep 27 '17 at 15:54

-1

Simply run JSON.parse(jsonString) to get an object from it

answered Sep 27 '17 at 15:54

Shardj

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Get values from JSON using javascript

4 Answers4