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JS parse object wrapped in a string using same quotes as object keys

Consider the following event payload data returned via WS:
{
id: "1",
foo: "{"bar":"baz"}"
}
The current output of JSON.stringify(event.foo):
"{\"bar\":\"baz\"}"
Also consider the backend have no real way to return the foo value formatted differently and I need to find a way to parse the string associated to this foo key in order to access it's value of bar.
The identified problem is the fact that the quotes used to wrap the whole supposed object are the sames used in the object itself, resulting in making JSON.parse() impossible.
I'm wondering if there is a "clean" way to achieve this.
So far, I tried:
using JSON.parse() which fails due to the format of the string raising Unexpected end of JSON input
trimming external quotes and converting inner ones to single then parsing, results in same error.
using new Object(...) based on the string (trimmed of external quotes)
replacing all quotes with single ones and wrapping it again in double ones to parse it.
Any input appreciated

The problem here is the backend should really be fixed, but some reason you can not do it. Next issue is you can "fix it" on the front end, but you are putting a band aid on the problem and it will fall off when the data that comes back is not what you expect. So the solutions will be error prone unless you know the data coming back will be a specific type.
With this said, you can fix the invalid JSON that you have in your simple example with a couple of regular expressions. Problem is, if your data contains characters such as } in the text, this is going to fail.
var response = `
{
id: "1",
foo: "{"bar":"baz"}",
goo: "{"gar":"gaz"}"
}
`
var reObj = /"(\{[^}]*})"/
while (response.match(reObj)) {
response = response.replace(reObj, '$1')
}
var reKey = /^\s+(\S+):/m
while (response.match(reKey)) {
response = response.replace(reKey,'"$1":')
}
var obj = JSON.parse(response)
console.log(obj)

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);
}

Convert string to array in ajax call in javascript

I am making an ajax call and getting back result from array that looks like result = [one, two, three];
I need to convert this to an array and iterate it. Since my string has no quotes around values array isn't read correctly.
Here is my code, if you can please show me correct way to do it. Thanks.
xmlhttp.open("POST","SearchServlet", true);
xmlhttp.onreadystatechange =
function(){
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
resultData = xmlhttp.responseText;
// resultData = [one, two, three];
// need to make valid array to iterate it
for (var i = 0; i < resultData.length; i++) {
console.log(resultData[i]);
}
}
};

Hi "user" and welcome to SO. Thanks for the code sample and well-formatted question :)
Since HTTP requests use strings (they don't send arrays), the best way to send your response is in JSON format. You can then easily parse the JSON string into an array.
http://www.copterlabs.com/blog/json-what-it-is-how-it-works-how-to-use-it/
JSON is a really easy to use (usually) way to send strings and dump them into arrays and vice versa.
There's ways to do it in Java (which I assume is the language for your server-side code) and PHP (which many people use also) and every other language.
For some reason I recall the Java ones being more difficult to use than they should be, but hopefully I'm mistaken. Either way, it's not too hard to learn and will bring your code-fu to the next level for sure.
A hack-y, not correct, ugly way to do it using your raw string is:
// Remove first and last bracket
var data = resultData.substr(1, resultData.length - 2);
// Split the array
data = data.split(", ");
...but please don't do it this way, this is for educational purposes only (at the risk of a downvote). Also I haven't tested it but you get the idea.
Again, the best way to do it is change your design to use JSON everywhere.

Ideally, you would use the JSON.parse function, but since one, two, and three are not quoted, you will have to do some work.
You can run through each of the items in your square brackets and put double quotes around them, then call JSON.parse. Alternatively, do as Steve suggests and rewrite your server's handler to respond with proper JSON.
If they were quoted, JSON.parse would work like this:
> JSON.parse('["one", "two", "three"]')
["one", "two", "three"]

Try this, its a little more complex, but it'll work:
resultData = xmlhttp.responseText;
resultData = resultData.substring(1, resultData.length-1);
var resultArray = resultData.split(',');

Though I don't know exactly why you can't output a valid JSON (with quoted strings in your array), this little and dirty function can parse your "almost-array" to a valid one, by putting quotes and removing spaces, this function returns a real array.
function validArray(str){
return str
.replace(/[\[\]']+/g,"")
.split(",")
.map(function(v){
return v.replace(/^\s\s*/g, '').replace(/\s\s*$/g, '');
});
}
The best solution is to avoid this kind of parsing and respond with valid JSON. This way, you could simply do a JSON.parse and easily obtain a JS object.

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);

Fix JS object replacing/encoding of strings?

I have an object with a value that has spaces in it, and it gets replaced with an encoded string, like:
alldata["test"] will return "Long+name"
or something like
alldata["test"] will return "%BLong+name%B"
when it's set by using
alldata["test"] = "Long name" (or "[Long name]") via a series of code.
Am I missing something? I don't think using $.toEvalJSON is the right way to go because I haven't transformed the object into JSON. I'd rather not do a string.replace either because I'd have to capture every possible type of input that is encoded.
Thank you!

If your question is how to remove the encoding, you could always use
unescape(s)
See Escape and Unescape Functions

The issue is related to the fact that I failed to mention that the object was being assigned the string as a result of a .serialize() command. Hence a urldecode() will work perfectly.