JSON parsing syntax error with manually entered string - javascript

When I try to stringyfy
ABC
<a href="abc.co.dds">
dfsdsf
</a>
JSON gives me
"ABC\n\n dfsdsf\n"
but when I try
s=('"ABC\n\n dfsdsf\n"');
JSON.parse(s)
I get a SyntaxError: Unexpected token on my console
How can I parse a manually entered string with JSON?

From the JSON specification (second 2):
A JSON text is a serialized object or array.
Since you are starting with a string (and not an object or an array), a JSON serializer should (IMO) throw an exception instead of giving you an escaped string.
You can work around your problem by wrapping your string in { "data": your_string } before converting to JSON (using whatever syntax that language you are using supports for objects/hash maps/associative arrays/etc). Obviously, you'll need to access foo.data after parsing the JSON to a native object at the other end).

Related

JSON.parse : Bad control character in string literal

I think this is a basic question, but I can't understand the reason. in JSON, it's valid to has a special character like "asdfadf\tadfadf", but when try parse it, it's shown error.
eg. code:
let s = '{"adf":"asdf\tasdfdaf"}';
JSON.parse(s);
Error:
Uncaught SyntaxError: Bad control character in string literal in JSON at position 12
at JSON.parse (<anonymous>)
at <anonymous>:1:6
I need to understand what is the issue, and solution.
You have to take into account that \t will be involved in two parsing operations: first, when your string constant is parsed by JavaScript, and second, when you parse the JSON string with JSON.parse(). Thus you must use
let s = '{"adf":"asdf\\tasdfdaf"}';
If you don't, you'll get the error you're seeing from the actual tab character embedded in the string. JSON does not allow "control" characters to be embedded in strings.
Also, if the actual JSON content is being created in server-side code somehow, it's probably easier to skip building a string that you're immediately going to parse as JSON. Instead, have your code build a JavaScript object initializer directly:
let s = { "adf": "asdf\tasdfdaf" };
In your server environment there is likely to be a JSON tool that will allow you to take a data structure from PHP or Java or whatever and transform that to JSON, which will also work as JavaScript syntax.
let t = '{"adf":"asdf\\tasdfdaf"}';
var obj = JSON.parse(t)
console.log(obj)

How can I resolve JSON parsing error 'JSON.parse: bad control character in string literal'?

In NodeJS Backend, I send my data to client as:-
res.end(filex.replace("<userdata>", JSON.stringify({name:user.name, uid:user._id, profile:user.profile}) ))
//No error here and Object is stringified perfectly
//user is object returned in mongoDB's result
The JSON string looks like this:
{"name":"Rishavolva","uid":"5f3ce234fd83024334050872","profile":{"pic":{"small_link":"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJyZXBsaWNhcyI6MiwidXJpcyI6W3siZGJfbmFtZSI6ImlmcmRiMDAxIiwidGFibGUiOiJGSUxFIiwiaWQiOjQ4fSx7ImRiX25hbWUiOiJpZnJkYjAwMiIsInRhYmxlIjoiRklMRSIsImlkIjo0OH1dLCJ1aWRfd2hpdGVsaXN0IjoiKiIsImlhdCI6MTU5ODE2MzMzNX0.9NkGnEumn4JW8IN0KFgxgN_6_4wN8qOgezNTyzz9osY","big_link":"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJyZXBsaWNhcyI6MiwidXJpcyI6W3siZGJfbmFtZSI6ImlmcmRiMDAxIiwidGFibGUiOiJGSUxFIiwiaWQiOjQ3fSx7ImRiX25hbWUiOiJpZnJkYjAwMiIsInRhYmxlIjoiRklMRSIsImlkIjo0N31dLCJ1aWRfd2hpdGVsaXN0IjoiKiIsImlhdCI6MTU5ODE2MzMzNX0.yxQ1GrhLsWPn8Qwu42EfTDXqaYwFtrM6f_7cAH2eLRY"},"aboutme":"I am Rishav Bhowmik\r\nand this is navratna pulaow"}}
and that UID is just a mongodb's primary key as string, and other two base 64 strings are just JWT tokens.
Now, when this JSON string reaches the Browser, I parse it with simple:
JSON.parse(`<userdata>`)
//remember I used filex.replace("<userdata>", JSON.stringify...) in the server
For reference, my MongoDB Document here is:
Now when JSON.parse is executed on the JSON string it will look like this on final JS code.
JSON.parse(`{"name":"Rishavolva","uid":"5f3ce234fd83024334050872","profile":{"pic":{"small_link":"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJyZXBsaWNhcyI6MiwidXJpcyI6W3siZGJfbmFtZSI6ImlmcmRiMDAxIiwidGFibGUiOiJGSUxFIiwiaWQiOjQ4fSx7ImRiX25hbWUiOiJpZnJkYjAwMiIsInRhYmxlIjoiRklMRSIsImlkIjo0OH1dLCJ1aWRfd2hpdGVsaXN0IjoiKiIsImlhdCI6MTU5ODE2MzMzNX0.9NkGnEumn4JW8IN0KFgxgN_6_4wN8qOgezNTyzz9osY","big_link":"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJyZXBsaWNhcyI6MiwidXJpcyI6W3siZGJfbmFtZSI6ImlmcmRiMDAxIiwidGFibGUiOiJGSUxFIiwiaWQiOjQ3fSx7ImRiX25hbWUiOiJpZnJkYjAwMiIsInRhYmxlIjoiRklMRSIsImlkIjo0N31dLCJ1aWRfd2hpdGVsaXN0IjoiKiIsImlhdCI6MTU5ODE2MzMzNX0.yxQ1GrhLsWPn8Qwu42EfTDXqaYwFtrM6f_7cAH2eLRY"},"aboutme":"I am Rishav Bhowmik\r\nand this is navratna pulaow"}}`)
I get this error:
Uncaught SyntaxError: JSON.parse: bad control character in string literal at line 1 column 702 of the JSON data
the string at position 702 of the JSON string is \n
First of all, how can \n be a control character?
What should I do to resolve this?
Has this problem arrised due to MONGODB result?
\n is a control character signifying a new line. In JSON, those control characters (more specifically the \) must be escaped inside strings.
This will raise the error:
JSON.parse(`{"hello":"world\n"}`)
This wont:
JSON.parse(`{"hello":"world\\n"}`)
So one way would be to use something like replace to ensure your aboutme is properly escaped before JSON serialization. See: How to escape a JSON string containing newline characters using JavaScript?
Ok have done some experimentation and have a solution.
The Trick is to do JSON.stringify() twice,
Like,
html_text.replace('/*<whatever>*/', JSON.stringify( JSON.stringify(the_object) ) )
If suppose html_text has a line which is
<script>
const object_inbrowser = JSON.parse(/*<whatever>*/)
// no need to add qotes, `JSON.stringify` in the server will do that for you
</script>

parse json string with forward slashes - javascript

Looks pretty simple but I am unable to figure it out
var str="[{name:\"House\",id:\"1\"},{name:\"House and Land\",id:\"5\"},{name:\"Land\",id:\"6\"},{name:\"Terrace\",id:\"11\"}]";
JSON.parse(str.replace(/\s/g, "").replace(/\//g, ''));
I am unable to the convert above string(which comes from 3rd party website) to valid json so that I can iterate it on my side
error
VM5304:1 Uncaught SyntaxError: Unexpected token n in JSON at position 2
at JSON.parse (<anonymous>)
JSON requires the keys to be quoted. It appears that your keys are coming in unquoted. So add another .replace statement to insert the quote back in:
.replace(/(\w+):/g, '"$1":');
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON
Property names must be double-quoted strings; trailing commas are forbidden.
COMPLETE SOLUTION:
.replace(/(,|{)\s*(\w+)\s*:/g, '$1"$2":');

JSON.parse fails to create an object from a string

I am using ruby on rails to create a cookie that returns an array containing the params of the request back to the view as a string. However, I get the following error when I JSON.parse that string:
JSON.parse('%7B%22specialty%22%3A%5B%22Anesthesiology%22%5D%7D')
Uncaught SyntaxError: Unexpected token % in JSON at position 0
how do I fix this?
The string is not valid json.
It is uri encoded so decode it using decodeURIComponent()
JSON.parse(decodeURIComponent('%7B%22specialty%22%3A%5B%22Anesthesiology%22%5D%7D'))
Other answers are correct in saying that the payload is URI encoded, but decodeURIComponent is only a javascript method. To decode it ruby-side, use URI.unescape.
JSON.parse(URI.unescape('%7B%22specialty%22%3A%5B%22Anesthesiology%22%5D%7D'))
You say you're using rails, so the URI object should already be available, but if you weren't using rails you would need to require 'uri' first.
You need to use decodeURIComponent to first decode the string.
JSON.parse(decodeURIComponent(
'%7B%22specialty%22%3A%5B%22Anesthesiology%22%5D%7D'
));
As the string is encoded. Once you decode it, you get the key value pair, i.e. the object in the form of a string. Now you can use JSON.parse to form the Javascript object.

JSON Lint says it's valid but JSON.parse throws error

I have simple JSON that I need to parse to object. Strangely it doesn't work even though if I copy and paste my JSON string to JSONLint (http://jsonlint.com/) it will show that it's valid.
var string = '{"token":"9eebcdc435686459c0e0faac854997f3","email":"201403050007950","id":"13","updated_at":"2014-03-05 10:34:51","messageguides":"[{\"name\":\"Un-named Messaging Guide 1\",\"pages\":[\"sustainabilitydirectors\",\"marketingnbusinessdevelopmentdirectors\"],\"date\":1394015692958}]"}';
var obj = JSON.parse(string); // Unexpected token n
console.log(obj);
The \ characters in the data are treated as JSON escape characters when you parse the raw JSON.
When you embed that JSON inside a JavaScript string, they are treated as JavaScript escape characters and not JSON escape characters.
You need to escape them as \\ when you express your JSON as a JavaScript string.
That said, you are usually better off just dropping the JSON in to the JavaScript as an object (or array) literal instead of embedding it in a string and then parsing it as a separate step.
var obj = {"token":"9eebcdc435686459c0e0faac854997f3","email":"201403050007950","id":"13","updated_at":"2014-03-05 10:34:51","messageguides":"[{\"name\":\"Un-named Messaging Guide 1\",\"pages\":[\"sustainabilitydirectors\",\"marketingnbusinessdevelopmentdirectors\"],\"date\":1394015692958}]"};

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