Best way to convert string to array of object in javascript?

Question

Hi guys, I want to convert below string to an array in javascript.

{a:12, b:c, foo:bar}

How do I convert this string into array of objects? Any cool idea?

Answer 1

The simplest, but unsafe way to do it is:

eval('(' + myJSONtext + ')')

But since this will interpret any javascript code, it has security holes. To protect against this use a json parser. If you're using a framework (jquery, mootools, etc.) there's a framework-specific call. Most of them are based on Douglas Crawford's parser available at http://www.json.org/js.html.

Answer 2

You can use "for in"

var myObject = {a:'12', b:'c', foo:'bar'};
var myArray = [];

for(key in myObject) {
    var value = myObject[key];
    myArray[key] = value;
}

myArray['a']; // returns 12

Notes: considering that myObject only have one level of key-value pairs.

Answer 3

I think that the best way of doing this, as Douglas Crockford (one of the biggests gurus of JavaScript) suggests in here is using the JSON native parser, as it is not only faster than the eval(), it's also more secure.

Native JSON parser is already available in:

• Firefox 3.5+
• IE 8+
• Opera 10.5+
• Safari Safari 4.0.3+
• Chrome (don't know which version)

And Crockford has made a safe fallback in javascript, called json2.js, which is an adaption of the eval() approach, with some security bits added and with the native JSON parsers API. You just need to include that file, remove its first line, and use the native JSON parser, and if it's not present json2 would do the work.

Here is an example:

var myJSONString = '{ "a": 1, "b": 2 }',
    myObject = JSON.parse(myJSONString);

Once parsed you'll get an object with attributes a and b, and as you may know, you can treat an object as a hash table or associative array in JavaScript, so you would be able to access the values like this:

myObject['a'];

If you just want a simple array and not an associative one you could do something like:

var myArray = [];
for(var i in myObject) {
    myArray.push(myObject[i]);
}

Lastly, although not necessary in plain JavaScript, the JSON spec requires double quoting the key of the members. So the navite parser won't work without it. If I were you I would add it, but if it is not possible use the var myObject = eval( "(" + myString + ")" ); approach.

Answer 4

If you're using jQuery, there's the $.parseJSON() function. It throws an exception if the string is malformed, and "Additionally if you pass in nothing, an empty string, null, or undefined, 'null' will be returned from parseJSON. Where the browser provides a native implementation of JSON.parse, jQuery uses it to parse the string"

Answer 5

Since your string is malformed JSON, a JSON parser can't parse it properly and even eval() will throw an error. It's also not an Array but a HashMap or simply an Object literal (malformed). If the Object literal will only contain number and string values (and no child objects/arrays) you can use the following code.

function malformedJSON2Array (tar) {
    var arr = [];
    tar = tar.replace(/^\{|\}$/g,'').split(',');
    for(var i=0,cur,pair;cur=tar[i];i++){
        arr[i] = {};
        pair = cur.split(':');
        arr[i][pair[0]] = /^\d*$/.test(pair[1]) ? +pair[1] : pair[1];
    }
    return arr;
}

malformedJSON2Array("{a:12, b:c, foo:bar}");
// result -> [{a:12},{b:'c'},{foo:'bar'}]

That code will turn your string into an Array of Objects (plural).

If however you actually wanted a HashMap (Associative Array) and NOT an array, use the following code:

function malformedJSON2Object(tar) {
    var obj = {};
    tar = tar.replace(/^\{|\}$/g,'').split(',');
    for(var i=0,cur,pair;cur=tar[i];i++){
        pair = cur.split(':');
        obj[pair[0]] = /^\d*$/.test(pair[1]) ? +pair[1] : pair[1];
    }
    return obj;
}

malformedJSON2Object("{a:12, b:c, foo:bar}");
// result -> {a:12,b:'c',foo:'bar'}

The above code will become a lot more complex when you start nesting objects and arrays. Basically you'd have to rewrite JSON.js and JSON2.js to support malformed JSON.

Also consider the following option, which is still bad I admit, but marginally better then sticking JSON inside an HTML tag's attribute.

<div id="DATA001">bla</div>
<!-- namespacing your data is even better! -->
<script>var DATA001 = {a:12,b:"c",foo:"bar"};</script>

I am assuming you omit quote marks in the string because you had put it inside an HTML tag's attribute and didn't want to escape quotes.