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The image below shows a debugging of a function in Chrome DevTools:
I realized that the data returned from the PHP file always has an arrow before the string as seen in the above. What causes this?
This poses a big issue for me. For example when comparing the string. Whenever I use
if(data == "success")
the statement in that block won't run because it would be false. The code I use in the PHP file is:
echo 'success';
That value is coming from the server. You need to fix the the code there so that it generates the correct response. It's likely you have some line breaks at the beginning of the PHP file you're calling which should be removed.
That said, you can trim whitespace from the response in JS:
if (data.trim() == 'success')
I would also suggest you amend your server code so that you return something other than plain text, because, as you've seen, text can easily be affected by whitespace.
Try returning JSON instead. You can then use a boolean flag in the response and avoid the rather ugly comparison to an arbitrary string.
Use trim() function
if (data.trim() === 'success')
Side note: Make habit of using === where possible
from API side, if accessible then check your return value
Instead of returning a string you may want to return a JSON object.
That will help you because like Rory said you can use booleans and also return multiple variables to your page. Accessing a JSON object with JS is easy.
In order to do that simply create a PHP array, add the data you want in it. Then when you want to return the array use json_encode() to return a JSON representation of your array.
PHP code (AJAX target file)
$return = array(
'status' => true
);
echo json_encode($return);
JS (callback function)
if(response.status) {
console.log('success')
}
How can i parse some object that stringify twice?
Most of the time in my code it is not problem but some times it stringify twice, and I can not trace the code to find my problem.
My JSON object something like this:
""[{\"name\":\"trane\",\"price\":\"150000\",\"order\":\"\",\"sale\":\"\",\"printedPic\":\"\",\"remainingPic\":\"\",\"locationEncome\":\"\"}]""
It's definitely best to figure out where and why it's stringifying twice, but you can just parse twice if you have to.
JSON.parse(JSON.parse("JSON STRING HERE"))
Edit
Potentially you're stringifying an already stringified object, this could help you figure out what is going wrong.
Add this function to your code and then replace your JSON.stringify calls to JSON.stringifyIfObject calls. Just use this as a means of debugging though, I wouldn't put this into production.
JSON.stringifyIfObject = function stringifyIfObject(obj){
if(typeof obj == "object")
return JSON.stringify(obj);
else{
alert("found already stringified object")
return obj;
}
}
This post is a little bit old but I had the same problem today and it was caused by a third party library.
Javascript library Prototype.js applies JSON.stringify() twice when it is used in version 1.6.x (it seems that this bug was removed in version 1.7)
The following code :
var test = ["banana"];
JSON.stringify(test);
will give you the following result :
""[\"banana\"]""
instead of (normally expected) :
"["banana"]"
Here is my source :
https://github.com/krinkle/jquery-json/issues/35
If that happens to you, the best option is to upgrade that library if you can.
I use JQuery to get Json data, but the data it display has double quotes. It there a function to remove it?
$('div#ListingData').text(JSON.stringify(data.data.items[0].links[1].caption))
it returns:
"House"
How can I remove the double quote? Cheers.
Use replace:
var test = "\"House\"";
console.log(test);
console.log(test.replace(/\"/g, ""));
// "House"
// House
Note the g on the end means "global" (replace all).
For niche needs when you know your data like your example ... this works :
JSON.parse(this_is_double_quoted);
JSON.parse("House"); // for example
The stringfy method is not for parsing JSON, it's for turning an object into a JSON string.
The JSON is parsed by jQuery when you load it, you don't need to parse the data to use it. Just use the string in the data:
$('div#ListingData').text(data.data.items[0].links[1].caption);
Someone here suggested using eval() to remove the quotes from a string. Don't do that, that's just begging for code injection.
Another way to do this that I don't see listed here is using:
let message = JSON.stringify(your_json_here); // "Hello World"
console.log(JSON.parse(message)) // Hello World
I also had this question, but in my case I didn't want to use a regex, because my JSON value may contain quotation marks. Hopefully my answer will help others in the future.
I solved this issue by using a standard string slice to remove the first and last characters. This works for me, because I used JSON.stringify() on the textarea that produced it and as a result, I know that I'm always going to have the "s at each end of the string.
In this generalized example, response is the JSON object my AJAX returns, and key is the name of my JSON key.
response.key.slice(1, response.key.length-1)
I used it like this with a regex replace to preserve the line breaks and write the content of that key to a paragraph block in my HTML:
$('#description').html(studyData.description.slice(1, studyData.description.length-1).replace(/\\n/g, '<br/>'));
In this case, $('#description') is the paragraph tag I'm writing to. studyData is my JSON object, and description is my key with a multi-line value.
You can simple try String(); to remove the quotes.
Refer the first example here: https://www.w3schools.com/jsref/jsref_string.asp
Thank me later.
PS: TO MODs: don't mistaken me for digging the dead old question. I faced this issue today and I came across this post while searching for the answer and I'm just posting the answer.
What you are doing is making a JSON string in your example. Either don't use the JSON.stringify() or if you ever do have JSON data coming back and you don't want quotations, Simply use JSON.parse() to remove quotations around JSON responses! Don't use regex, there's no need to.
I dont think there is a need to replace any quotes, this is a perfectly formed JSON string, you just need to convert JSON string into object.This article perfectly explains the situation : Link
Example :
success: function (data) {
// assuming that everything is correct and there is no exception being thrown
// output string {"d":"{"username":"hi","email":"hi#gmail.com","password":"123"}"}
// now we need to remove the double quotes (as it will create problem and
// if double quotes aren't removed then this JSON string is useless)
// The output string : {"d":"{"username":"hi","email":"hi#gmail.com","password":"123"}"}
// The required string : {"d":{username:"hi",email:"hi#gmail.com",password:"123"}"}
// For security reasons the d is added (indicating the return "data")
// so actually we need to convert data.d into series of objects
// Inbuilt function "JSON.Parse" will return streams of objects
// JSON String : "{"username":"hi","email":"hi#gmail.com","password":"123"}"
console.log(data); // output : Object {d="{"username":"hi","email":"hi#gmail.com","password":"123"}"}
console.log(data.d); // output : {"username":"hi","email":"hi#gmail.com","password":"123"} (accessing what's stored in "d")
console.log(data.d[0]); // output : { (just accessing the first element of array of "strings")
var content = JSON.parse(data.d); // output : Object {username:"hi",email:"hi#gmail.com",password:"123"}" (correct)
console.log(content.username); // output : hi
var _name = content.username;
alert(_name); // hi
}
I had similar situation in a Promise just solved doing a cast as (String)
export async function getUserIdByRole(userRole: string): Promise<string> {
const getRole = userData.users.find((element) => element.role === userRole);
return String (getRole?.id);
}
I have this JSon string received from an AJAX call:
{status:OK,addresses:[0,1,2,3,4,5]}
To convert it to a JSon object I have this line:
var jsonObj = eval(jsonString);
But an exception is thrown! This one has no message in the exception variable.
I also tried using
{"status":"OK","addresses":[0,1,2,3,4,5]}
And, yet again, an exception is thrown but saying that an unexpected character '&' was found.
I'm using Struts2 and the JSon is received from an action.
Any help will be appreciated.
Thank you
{status:OK,addresses:[0,1,2,3,4,5]}
is not valid JSON because the quotes around status and addresses are missing, and is neither valid JSON nor valid JavaScript since the quotes around OK are missing.
Also, don't use eval to parse JSON - it allows an attacker to execute arbitrary JavaScript in the context of your page. Instead, use the safe alternatives JSON.parse(built-in in modern browsers and other EcmaScript 5 implementations) or JSON2.
Don't use eval: use a proper JSON parser such as JSON2.
You probably have extra content in the response: check that you are not printing anything else out.
This is working for me:
JSON.parse('{ "status" : "OK", "addresses" : [0,1,2,3,4,5]}');
If you want to use eval, then you need to use the second example you posted ({"status":"OK","addresses":[0,1,2,3,4,5]}) and you need to surround the string with parenthesis as such:
var jsonObj = eval( '('+jsonString+')' );
This makes jsonString a valid javascript statement.
With that being said, I encourage you use JSON.parse, as many others have posted. It is far more secure.
You don't have a JSON string. You do have an object literal. You need the names to have quotes.
{"status":OK, "addresses":[0,1,2,3,4,5]}
Based on this comment:
So I verified that when JSon is received from the request, all the " are replaced by " ... could this be the problem?
Yes. A JSON parser expects to receive JSON as input, not HTML encoded JSON.
Two issues to fix:
Add quotes around the "OK" to make it a legal javascript string.
Add parens around the string before sending to eval like this eval("(" + jsonString + ")")';
This:
{status:OK,addresses:[0,1,2,3,4,5]}
would have to be changed to this:
{status:"OK",addresses:[0,1,2,3,4,5]}
to be valid Javascript (note the quotes around "OK").
It should be this to be valid JSON (quotes around the keys too):
{"status":"OK", "addresses":[0,1,2,3,4,5]}
OK all by itself is not a known piece of Javascript without the quotes around it to make it into a Javascript string. In the future, you can test yourself in a small test bed and see what the error is in your favorite javascript debugger:
http://jsfiddle.net/jfriend00/FcSKR/
var jsonString = '{"status":"OK","addresses":[0,1,2,3,4,5]}';
var jsonObj = eval("(" + jsonString + ")");
alert("success");
If you still get an error with {"status":"OK","addresses":[0,1,2,3,4,5]} and the adding of parens before sending to eval, then your data isn't what you think it is and you need to do some debugging to see exactly what is in the response (look at the value in the debugger, put the value into an alert, etc...). There is probably some other stuff in the response that you didn't know would be there.
Note: there are some situations where a JSON parser like JSON.parse() and a legal JSON string is safer than eval() with Javascript that can be anything.
I am really stuck in parsing a JSON string and take it's values. I got the JSON string as
{"user":{"id":"1","firstname":"Freelogin","created":"0000-00-00 00:00:00","lastname":"Administrator","email":"fred#websecurify.com", "usergroup_id":"1","status":"1","ip_enable":"N","priv":"0","expire":""},"data":{ "1":{"5":{"last_update":"2010-12-13 16:16:16","status":"0"},"3":{"last_update":"2010-12-13 16:41:48","status":"1"}},"2":{"6":{"last_update":"2010-12-13 16:41:48","status":"1"}}},"server_array":[{"id":"1","name":"anes.yyy.net"},{ "id":"2","name":"neseema.xxx.net"}],"service_array":[{"id":"5","name":"POP3"}, {"id":"6","name":"Cpanel"},{"id":"3","name":"SMTP"}],"sort_by":"servername", "sort_order":"ASC","pagelinks":"","totrows":"2","offset":"0","limitvalue":"10", "rows_monitor":2,"current":"monitor","uri":false}
How to Parse this and take the Results for further
processing in JavaScript
You should use jQuery.parseJSON. It will use native JSON if available, and only use eval if necessary, after a sanity check.
Use JSON.parse (redirected from http://json.org), alternatively MDN
Json is already some javascript. so parsing is just using eval
like:
var foobar = eval(yourjson);
alert(foobar.user);
Also jquery has some function for it jquery.parseJSON
like:
var foobar = $.parseJSON(yourjson);
Jquery is better because it would make some checks and perform better.
First, download jQuery.
Second, include it in your page.
Third, if your variable is this:
var jsonString = '{"user":{"id":"1","firstname":"Freelogin","created":"0000-00-00 00:00:00","lastname":"Administrator","email":"fred#websecurify.com", "usergroup_id":"1","status":"1","ip_enable":"N","priv":"0","expire":""},"data":{ "1":{"5":{"last_update":"2010-12-13 16:16:16","status":"0"},"3":{"last_update":"2010-12-13 16:41:48","status":"1"}},"2":{"6":{"last_update":"2010-12-13 16:41:48","status":"1"}}},"server_array":[{"id":"1","name":"anes.yyy.net"},{ "id":"2","name":"neseema.xxx.net"}],"service_array":[{"id":"5","name":"POP3"}, {"id":"6","name":"Cpanel"},{"id":"3","name":"SMTP"}],"sort_by":"servername", "sort_order":"ASC","pagelinks":"","totrows":"2","offset":"0","limitvalue":"10", "rows_monitor":2,"current":"monitor","uri":false}';
then,
var parsedJson = jQuery.parseJSON(jsonString);
will give you the desired parsed object that's ready for manipulation.
I tried out your JSON string on JSONLint and it says it's valid, so you should have no problems with it.
you probably got your json in som String variable
var json = '{"user":{"id":"1","firstname":"Freelogin","created":"0000-00-00 00:00:00","lastname":"Administrator","email":"fred#websecurify.com", "usergroup_id":"1","status":"1","ip_enable":"N","priv":"0","expire":""},"data":{ "1":{"5":{"last_update":"2010-12-13 16:16:16","status":"0"},"3":{"last_update":"2010-12-13 16:41:48","status":"1"}},"2":{"6":{"last_update":"2010-12-13 16:41:48","status":"1"}}},"server_array":[{"id":"1","name":"anes.yyy.net"},{ "id":"2","name":"neseema.xxx.net"}],"service_array":[{"id":"5","name":"POP3"}, {"id":"6","name":"Cpanel"},{"id":"3","name":"SMTP"}],"sort_by":"servername", "sort_order":"ASC","pagelinks":"","totrows":"2","offset":"0","limitvalue":"10", "rows_monitor":2,"current":"monitor","uri":false}';
now you can easily parse it via jQuery (you also can parse it via native javaScript eval, but there are some security issues, badly formated input string f.e., that is covered with jQuery and not in eval)
result = jQuery.parseJSON(json);
Now you can easily acces your json object
alert('Hello user, your name is ' + json.user.firstname);
You don't need jQuery, in ECMAScript5 JSON object will be supported natively and with it you can use JSON.parse method to parse a string into a JS object. IE9 will support ES5 and FF and Chrome already do.
For the moment you can use json2.js (you can look at the source here) as fallback for the browsers that don't support JSON natively.