How to parse JSON of String Arrays

Question

I have ajax code which returns JSON data which is just Array of string(no key/val pair).

function loadData() {
    $.ajax({
    type: 'GET',
    url: apiURL,
    dataType: "json",
    timeout: 2000,
    success: onLoadData
};

function onLoadData(data) {
    console.log(data);
    var arr = JSON.parse(data);
    //var arr = jQuery.parseJSON(data); this also fails.
    alert(arr[0]);
};

Output of console.log() is = ["one", "two", "three"] but JSON.parse() gives error as :

Uncaught SyntaxError: Unexpected token o

I checked JSON using validator which says this is valid JSON. Can someone help to understand why parse() is failing?

It's an array already, you cannot JSON.parse() an array. If you specify dataType: "json" jquery parses it for you. — zerkms
– zerkms, Commented Dec 17, 2014 at 20:25
Setting your dataType to json automatically parses the response as json — tymeJV
– tymeJV, Commented Dec 17, 2014 at 20:25

Aweary · Accepted Answer · 2014-12-17 20:25:51Z

4

Just remove JSON.parse(data) if its already an array. You'll see that your alert call should work fine.

answered Dec 17, 2014 at 20:25

Aweary

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2 Comments

Erik Philips Over a year ago

The reason WHY this works is in the documentation of jQuery's ajax.

The function gets passed three arguments: The data returned from the server, formatted according to the dataType parameter...

. The dataType states

If none is specified, jQuery will try to infer it based on the MIME type of the response (an XML MIME type will yield XML, in 1.4 JSON will yield a JavaScript object,...

. So jQuery by default usually decodes a JSON string into a Javascript Object.

vinitb4u Over a year ago

thanks @ErikPhilips for details. Yes I found that parse() needs developer.mozilla.org/en/docs/Web/JavaScript/Reference/… parameter of type string and because typeof(data) is object, using var string_data = JSON.stringify(data); solves the issue so as said in above answers "data" is alerady array it need not to parse.

Eduard · Accepted Answer · 2014-12-17 20:39:27Z

0

Just do:

alert(data[0]) // and remove everything else in that callback.

You're already fine with that dataType : "json".

answered Dec 17, 2014 at 20:39

Eduard

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