For some reason this formated JSON always fail for me when I try to use JSON.parse().
let string = '[{"appearances":{"0":[138545,""],"1":[138547,""],"3":[138548,""]},"bonustrees":[240,241,264],"classs":2,"displayid":138545,"dps":18.67,"flags2":8192,"id":113965,"level":138,"name":"4Sorkas Chainfist","reqlevel":100,"slot":13,"slotbak":13,"source":[2],"sourcemore":[{"bd":1,"z":6967}],"specs":[269,581,260,263,577],"speed":2.60,"subclass":13,modes:{"mode":458752,"4":{"count":229,"outof":21731},"65536":{"count":28,"outof":4490},"131072":{"count":18,"outof":4719},"262144":{"count":183,"outof":3517}},count:229,stack:[1,1]}]';
console.log(eval(string)); // Output as expected from JSON.parse
console.log(JSON.parse(string)); // SyntaxError: Unexpected token m in JSON at position 341
JSON.parse fails because it can only process JSON syntax. Your string is not a valid JSON -- it says so in the error message you're receiving.
The error points to an m from the modes from this part:
"subclass":13,modes:{"mode":458752,
You've also got a couple of more quotes missing down the line; you might want to check that out.
eval executes JavaScript code passed in as a string -- as if you've written it in code in the place where you're running the function. Since your string is valid JavaScript, it works without a problem.
Related
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)
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>
I have the following data coming in from my server into my js code, from my server.
{"triggers": [{"message_type": "sms","recipients": "[\"+91xxxxxxxxx\",\"+91xxxxxxxxx\"]","message": "This is a test"}]}
My code parses the above json string in the following manner.
data = '{"triggers": [{"message_type": "sms","recipients": "[\"+91xxxxxxxx\",\"+91xxxxxxxx\"]","message": "This is a test"}]}'
parsed = JSON.parse(data);
This throws the following exception
Uncaught SyntaxError: Unexpected token + in JSON at position 54
at JSON.parse (<anonymous>)
at eval (eval at <anonymous> (entry.html:2), <anonymous>:1:6)
at entry.html:298
I did a little bit of further digging and found the source of the json string.
Here is where the string is coming in from my python code
data = {"recipients": "[\"+91xxxxxxxxx\",\"+91xxxxxxxx\"]"} # This data comes in from my database, and I can't do anything about what quotes are used.
javascript_supplied_data = json.dumps(data) #This data goes to the frontend via webhook
I tried putting the same data into a json view via this online viewer, and it didn't throw any error and displayed the data correctly.
What I can't understand is, I am doing a json.dumps in my python code, so the string response should be json parsable. So why does JSON.parse throw this error?
Is there something wrong with the json libraries at the python end or the javascript end, or am I too much of a noob?.
Please help me figure out what is causing this issue, and how to solve it.
NOTE: I don't have any control over the string that comes in from the server.
When you have valid JSON, but put it in a string literal, the escapes treated by the literal notation in JavaScript make the string different. The backslashes are interpreted as for escaping the next character.
So either you have to go through the string literal and double all the backslashes, or you can apply String.raw to the string literal as template string:
var data = String.raw`{"triggers": [{"message_type": "sms","recipients": "[\"+91xxxxxxxx\",\"+91xxxxxxxx\"]","message": "This is a test"}]}`;
var parsed = JSON.parse(data);
console.log(parsed);
Note however, that the JSON you posted at the start of your question is valid.
On the other hand, the error you get indicates that the \" just before the first + is interpreted as just ". This means the \ is not actually there when the string is received from the server. This is usually caused by a similar escaping problem at the server side, where the programmer intended to send the backslash to the client, but actually just escaped the " on the server, which resulted in only the " being sent to the client and not \".
You have to use single quotes here while escape sequence.
if we use double quotes for escape sequence here it will result in
"recipients": "["+91xxxxxxxx","+91xxxxxxxx"]"
double quotes inside double quotes which is why your code breaks.
data = '{"triggers": [{"message_type": "sms","recipients": "[\'+91xxxxxxxx\',\'+91xxxxxxxx\']","message": "This is a test"}]}';
parsed = JSON.parse(data);
console.log(parsed)
I have a JSON data as below which getting from remote URL.
{"myitems":[{\"NAME\":\"JOHN\"},{\"NAME\":\"MICHAEL\"},{\"NAME\":\"CATTY\"},{\"NAME\":\"DAVID\"}]}
in JavaScript I want to parse
JSON.parse(mydata);
But I'm getting the error as:
Invalid Character
What can I do?
You need to fix the errors in the JSON. This fix should be done at source (i.e. you should change the report URL that is outputting invalid JSON so it outputs valid JSON instead).
Your string literals need to start and end with " (not \"). With the exception of "myitems", all of them have that error.
You have to remove slashes this will fix your issue:
Ex:
var str='{"myitems":[{\"NAME\":\"JOHN\"},{\"NAME\":\"MICHAEL\"},{\"NAME\":\"CATTY\"},{\"NAME\":\"DAVID\"}]}';
var output=JSON.parse(str.replace(/\\/g, ""));
above example will gives you output.
suppose I have something like
var a = '["\t"]'
If I do
eval('var result = ' + a)
Everything works fine. But if I do
var result = JSON.parse(a)
It throws error: Unexpected token.
Same happens with \b, \f: works with eval, while fails with JSON.parse. Why? Shouldn't the parser behave in the same way when encounters "\t"?
On the other hand, both eval and JSON.parse fail with a \n (as expected), but they also both fail with a \r. Why is this?
I'm a little bit confused with all this so could anybody explain what is going on? If possible with details: how is the parser behaving in the two cases?
You have to escape \ in the JavaScript string, so you'd end up with
var a = '["\\t"]'
For details, please refer to "http://json.org/"
Well that's because it's not valid JSON.
Don't try to write JSON yourself. Instead, use JSON.stringify to properly encode your data.
var json = JSON.stringify(["\t"]);
JSON.parse(json);
//=> ["\t"]