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JSON.parse - How to handle capitalized Boolean values?

I am working on a Node.js application that needs to handle JSON strings and work with the objects.
Mostly all is well and JSON.parse(myString) is all I need.
The application also gets data from third parties. One of which seems to be developed with Python.
My application repeatable chokes on boolean values since they come captialized.
Example:
var jsonStr = "{'external_id': 123, 'description': 'Run #2944', 'test_ok': False}";
try{
var jsonObj = JSON.parse(jsonStr);
}catch(err){
console.err('Whoops! Could not parse, error: ' + err.message);
}
Notice the test_ok parameter - it all is good when it follows the Javascript way of having a lower case false boolean instead. But the capitalized boolean does not work out.
Of course I could try and replace capitalized boolean values via a string replace, but I am afraid to alter things that should not get altered.
Is there an alternative to JSON.parse that is a little more forgiving?

I don't mean to be rude but according to json.org, its an invalid json. That means you'll have to run a hack where you have to identify stringified boolean "True" and convert it to "true" without affecting a string that lets say is "True dat!"

First of all, I would not recommend using the code below. This is just to demonstrate how to convert your input string into a valid JSON. There were problems, one is the Boolean False, and another is the single quotes around property names. I'm not positive but I believe those need to be double quotes.
I don't believe having to convert a string into a valid JSON is a good choice. If you have no alternative, meaning you don't have access to the code generating this string, then the code below is still not a good choice because it will have issues if you have embedded quotes in the string values. i.e. you would need different string replace logic.
Keep all this in mind before using the code.
var jsonStr = "{'external_id': 123, 'description': 'Run #2944', 'test_ok': False}";
try {
jsonStr = jsonStr.replace(/:[ ]*False/,':false' ).replace( /'/g,'"');
var jsonObj = JSON.parse(jsonStr);
console.log( jsonObj );
} catch (err) {
console.err('Whoops! Could not parse, error: ' + err.message);
}

Converting a String into an Object

I'm receiving a string like obj{a="foo",b="bar",c=3,d=4.0} inside a nodejs environment I'm working in and I'm trying to convert this String into a reference-able Object like this:
{
a : "foo",
b : "bar",
c : 3,
d : 4.0
}
Assigned to obj of course.
I've used a myriad of formatting tricks but whenever I call JSON.parse() I get unexpected character errors. Usually on the first alpha-character it sees.
My next step is to write several nested loops to make all of the assignments manually but I'm hoping someone can point me in the right direction on how to parse this.
EDIT: Ok there's a little more to the story and I thought I should omit it but I guess explaining everything would be helpful.
The actual data packet that I'm receiving looks like this.
ack{a="000000061",b=0,c=2.0}\rb{a=244.0,b=255,c=4.0}\rc{a=6.0,b=55,c=55}endack;
So yeah that's the actual string I'm trying to parse into three distinct accessible Objects. I know I'm having a brain fart from a long day but yeah it's giving me a run for my money right now.

First replace the "=" with ":" and remove the obj infront
str = str.replace(/=/g, ":").replace("obj{", "{")
Since it's not in correct json format (but can be read by js parser) we can't use JSON.parse but we can use eval
eval("var obj = " + str);
Obvious there are some assumptions with this technique such that = always mean colon and you won't have obj{ as text (but the latter can be fixed with a simple substring method)
Keep in mind eval is also considered evil so use at your own risk. Imagine if the user were to send bad data, they could easily get into your parser and run something malicious. But hopefully this will give you an idea or inspiration to a better solution.
You can go a step further and use
str = 'obj{a="foo",b="bar",c=3,d=4.0}'
str = str.substr(3,str.length).replace(/([{,])([\w])=/g, '$1\"$2\":');
var obj = JSON.parse(str);

Parse ill formed JSON string

I am being sent an ill formed JSON string from a third party. I tried using JSON.parse(str) to parse it into a JavaScript object but it of course failed.
The reason being is that the keys are not strings:
{min: 100}
As opposed to valid JSON string (which parses just fine):
{"min": 100}
I need to accept the ill formed string for now. I imagine forgetting to properly quote keys is a common mistake. Is there a good way to change this to a valid JSON string so that I can parse it? For now I may have to parse character by character and try and form an object, which sounds awful.
Ideas?

You could just eval, but that would be bad security practice if you don't trust the source. Better solution would be to either modify the string manually to quote the keys or use a tool someone else has written that does this for you (check out https://github.com/daepark/JSOL written by daepark).

I did this just recently, using Uglifyjs to evaluate:
var jsp = require("uglify-js").parser;
var pro = require("uglify-js").uglify;
var orig_code = "var myobject = " + badJSONobject;
var ast = jsp.parse(orig_code); // parse code and get the initial AST
var final_code = pro.gen_code(ast); // regenerate code
$('head').append('<script>' + final_code + '; console.log(JSON.stringify(myobject));</script>');
This is really sloppy in a way, and has all the same problems as an eval() based solution, but if you just need to parse/reformat the data one time, then the above should get you a clean JSON copy of the JS object.

Depending on what else is in the JSON, you could simply do a string replace and replace '{' with '{"' and ':' with '":'.

Extracting values with Javascript

I have a variable called "result",
var result;
that result value is equal to following value, please presume that is just a string :)
---------result value -----------
for (;;);{
"send":1,
"payload":{
"config":{
"website":"",
"title":"welcome to site",
"website-module":1313508674538,
"manufatureid":"id.249530475080015",
"tableid":"id.272772962740259",
"adminid":100002741928612,
"offline":null,
"adminemail":"admin#website.com",
"adminame":"George",
"tags":"web:design:template",
"source":"source:design:web",
"sitelog":[],
"errorlog":0,
"RespondActionlog":0,
"map":null
},
"imgupload":""
},
"criticalerror":[0],
"report":true
}
---------result value------------
From that value, I would like to extract tableid which is "id.272772962740259" with classic Javascript.
How can I extract the code, please let me know how can i do with simple javascript, please don't use Jquery, all I just need is simple javascript.

You can simply evaluate the value of the variable to obtain the values. However, please note that your current value is not valid JSON; that for(;;); at the beginning of the value invalidates the format. Remove that, and you can do this:
var object = eval('(' + resultMinusThatForLoop + ')');
alert(object.payload.config.tableid);

If that data is a string the parse it with a JSON parse. The following should get the value you want
JSON.parse(result).payload.config.tableid; // "id.272772962740259"
Edit: though, as Tejs says, the for(;;) invalidates the string and stops it from being parsed. If you can remove that, do.

You need to remove the empty for loop, then parse the string. DO NOT use eval; most modern browsers provide built-in JSON-parsing facilities, but you can use json2.js if yours does not. Assuming that you assign the results of parsing the JSON to result, you should be able to get that value using result.payload.config.tableid.
You should probably read a good JS reference. JavaScript: The Good Parts or Eloquent JavaScript would be a good choice.

If result is a javascript object and not a string, you can just use 'result.payload.config.tableid'.
If it is not, how do you get the AJAX result? Are you using XmlHttpRequest directly? Most libraries will give you a javascript object, you might be missing a flag or not sending the response back with the right content type.
If it is a string and you want to parse it manually, you should use a JSON parser. Newer browsers have one built in as window.JSON, but there is open source code for parsing it as well.
var obj = JSON.parse(result);
alert('tableid is ' + obj.payload.config.tableid);

Should jQuery's parseJSON/getJSON methods be used?

I noticed that the jQuery parseJSON basically does a simple regex "check":
parseJSON: function( data ) {
if ( typeof data !== "string" || !data ) {
return null;
}
// Make sure leading/trailing whitespace is removed (IE can't handle it)
data = jQuery.trim( data );
// Make sure the incoming data is actual JSON
// Logic borrowed from http://json.org/json2.js
if ( /^[\],:{}\s]*$/.test(data.replace(/\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g, "#")
.replace(/"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g, "]")
.replace(/(?:^|:|,)(?:\s*\[)+/g, "")) ) {
// Try to use the native JSON parser first
return window.JSON && window.JSON.parse ?
window.JSON.parse( data ) :
(new Function("return " + data))();
} else {
jQuery.error( "Invalid JSON: " + data );
}
},
If it passes that "check" and if it's a modern browser a native JSON parser is used. Otherwise, I assume for a browser like IE6 a new function is automatically invoked and returns the object.
Question #1: Since this is just a simple regex test, isn't this prone to some sort of obscure edge-case exploit? Shouldn't we really be using a full blown parser, for the browsers that don't support native JSON parsing at least?
Question #2: How much "safer" is (new Function(" return " + data ))() as opposed to eval("(" + text + ")")?

As mentioned in the comments there jQuery's JSON parser "borrows" the logic that tests to see if the JSON string is valid, right from json2.js. This makes it "as safe" as the most common non-native implementation, which is rather strict anyway:
// In the second stage, we run the text against regular expressions that look
// for non-JSON patterns. We are especially concerned with '()' and 'new'
// because they can cause invocation, and '=' because it can cause mutation.
// But just to be safe, we want to reject all unexpected forms.
// We split the second stage into 4 regexp operations in order to work around
// crippling inefficiencies in IE's and Safari's regexp engines. First we
// replace the JSON backslash pairs with '#' (a non-JSON character). Second, we
// replace all simple value tokens with ']' characters. Third, we delete all
// open brackets that follow a colon or comma or that begin the text. Finally,
// we look to see that the remaining characters are only whitespace or ']' or
// ',' or ':' or '{' or '}'. If that is so, then the text is safe for eval.
if (/^[\],:{}\s]*$/.
test(text.replace(/\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g, '#').
replace(/"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g, ']').
replace(/(?:^|:|,)(?:\s*\[)+/g, ''))) {
What I don't understand is why jQuery runs the regular expression/replaces before checking for a native implementation which would check for correct JSON grammar anyway. It seems like it would speed things up to only do this if a native implementation isn't available.
Question 2 is answered very well by bobince in another question:
It's not really a big difference, but the feeling is that eval is ‘worse’ than new Function. Not in terms of security — they're both equally useless in the face of untrusted input, but then hopefully your webapp is not returning untrusted JSON strings — but in terms of language-level weirdness, and hence resistance to optimisation.
Check out Nick Craver's answer there too for a direct quote from John Resig.

The JSON.parse method is the safest. This is defined when you include json2.js from http://www.json.org/js.html and used automatically by parseJSON/getJSON. It parses instead of executing the JSON markup.