Can't parse JSON to Javascript object

Question

I have this HTML box:

<span>Select depatament</span><span>
    <select id="department" onchange="EnableSlaveSelectBox(this)" data-slaveelaments='{"a": 1, "b": "2"}'>
       <option selected disabled>-Select-</option>
    </select>
</span>

Event onchange() implementation:

function EnableSlaveSelectBox(element) {
    var d = $('#department').data('slaveelaments');
    alert($.parseJSON(d));
}

But when onchange() event is fired I get on this row:

alert($.parseJSON(d));

This error:

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

return JSON.parse( data + "" );

Any idea why I get error above?

Andy · Accepted Answer · 2015-05-11 15:49:12Z

3

Because, interestingly, jQuery seems to automatically parse the string to an object. To test this:

alert(d); // [object Object]

Or do this to see the stringified version again:

alert(JSON.stringify(d)); // {"a":1,"b":"2"}

Aside: I didn't know jQuery did that until I tested it.

answered May 11, 2015 at 15:49

Andy

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1 Comment

talemyn Over a year ago

I was just about to post the same thing . . . you learn something new every day. :) Nice feature jQuery guys!

charlietfl · Accepted Answer · 2015-05-11 15:49:36Z

2

jQuery data() will already convert properly formatted json to array or object.

This is as documented in APi

When the data attribute is an object (starts with '{') or array (starts with '[') then jQuery.parseJSON is used to parse the string; it must follow valid JSON syntax including quoted property names. If the value isn't parseable as a JavaScript value, it is left as a string.

data() API DOCS

answered May 11, 2015 at 15:49

charlietfl

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Comments

Oleksandr T. · Accepted Answer · 2015-05-11 15:53:21Z

1

In your case you don't need use parseJSON, because d is Object,

function EnableSlaveSelectBox(element) {
    var d = $('#department').data('slaveelaments');

    console.log(d.a);
    console.log(d.b);
}

Example

When the data attribute is an object (starts with '{') or array (starts with '[') then jQuery.parseJSON is used to parse the string; it must follow valid JSON syntax including quoted property names. If the value isn't parseable as a JavaScript value, it is left as a string.

$.data

edited May 11, 2015 at 15:53

answered May 11, 2015 at 15:48

Oleksandr T.

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