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This question already has answers here:
Safely turning a JSON string into an object
(28 answers)
Closed 7 years ago.
I want to parse a JSON string in JavaScript. The response is something like
var response = '{"result":true,"count":1}';
How can I get the values result and count from this?
The standard way to parse JSON in JavaScript is JSON.parse()
The JSON API was introduced with ES5 (2011) and has since been implemented in >99% of browsers by market share, and Node.js. Its usage is simple:
const json = '{ "fruit": "pineapple", "fingers": 10 }';
const obj = JSON.parse(json);
console.log(obj.fruit, obj.fingers);
The only time you won't be able to use JSON.parse() is if you are programming for an ancient browser, such as IE 7 (2006), IE 6 (2001), Firefox 3 (2008), Safari 3.x (2009), etc. Alternatively, you may be in an esoteric JavaScript environment that doesn't include the standard APIs. In these cases, use json2.js, the reference implementation of JSON written by Douglas Crockford, the inventor of JSON. That library will provide an implementation of JSON.parse().
When processing extremely large JSON files, JSON.parse() may choke because of its synchronous nature and design. To resolve this, the JSON website recommends third-party libraries such as Oboe.js and clarinet, which provide streaming JSON parsing.
jQuery once had a $.parseJSON() function, but it was deprecated with jQuery 3.0. In any case, for a long time, it was nothing more than a wrapper around JSON.parse().
WARNING!
This answer stems from an ancient era of JavaScript programming during which there was no builtin way to parse JSON. The advice given here is no longer applicable and probably dangerous. From a modern perspective, parsing JSON by involving jQuery or calling eval() is nonsense. Unless you need to support IE 7 or Firefox 3.0, the correct way to parse JSON is JSON.parse().
First of all, you have to make sure that the JSON code is valid.
After that, I would recommend using a JavaScript library such as jQuery or Prototype if you can because these things are handled well in those libraries.
On the other hand, if you don't want to use a library and you can vouch for the validity of the JSON object, I would simply wrap the string in an anonymous function and use the eval function.
This is not recommended if you are getting the JSON object from another source that isn't absolutely trusted because the eval function allows for renegade code if you will.
Here is an example of using the eval function:
var strJSON = '{"result":true,"count":1}';
var objJSON = eval("(function(){return " + strJSON + ";})()");
alert(objJSON.result);
alert(objJSON.count);
If you control what browser is being used or you are not worried people with an older browser, you can always use the JSON.parse method.
This is really the ideal solution for the future.
If you are getting this from an outside site it might be helpful to use jQuery's getJSON. If it's a list you can iterate through it with $.each
$.getJSON(url, function (json) {
alert(json.result);
$.each(json.list, function (i, fb) {
alert(fb.result);
});
});
If you want to use JSON 3 for older browsers, you can load it conditionally with:
<script>
window.JSON ||
document.write('<script src="//cdnjs.cloudflare.com/ajax/libs/json3/3.2.4/json3.min.js"><\/scr'+'ipt>');
</script>
Now the standard window.JSON object is available to you no matter what browser a client is running.
The following example will make it clear:
let contactJSON = '{"name":"John Doe","age":"11"}';
let contact = JSON.parse(contactJSON);
console.log(contact.name + ", " + contact.age);
// Output: John Doe, 11
If you pass a string variable (a well-formed JSON string) to JSON.parse from MVC #Viewbag that has doublequote, '"', as quotes, you need to process it before JSON.parse (jsonstring)
var jsonstring = '#ViewBag.jsonstring';
jsonstring = jsonstring.replace(/"/g, '"');
You can either use the eval function as in some other answers. (Don't forget the extra braces.) You will know why when you dig deeper), or simply use the jQuery function parseJSON:
var response = '{"result":true , "count":1}';
var parsedJSON = $.parseJSON(response);
OR
You can use this below code.
var response = '{"result":true , "count":1}';
var jsonObject = JSON.parse(response);
And you can access the fields using jsonObject.result and jsonObject.count.
Update:
If your output is undefined then you need to follow THIS answer. Maybe your json string has an array format. You need to access the json object properties like this
var response = '[{"result":true , "count":1}]'; // <~ Array with [] tag
var jsonObject = JSON.parse(response);
console.log(jsonObject[0].result); //Output true
console.log(jsonObject[0].count); //Output 1
The easiest way using parse() method:
var response = '{"a":true,"b":1}';
var JsonObject= JSON.parse(response);
this is an example of how to get values:
var myResponseResult = JsonObject.a;
var myResponseCount = JsonObject.b;
JSON.parse() converts any JSON String passed into the function, to a JSON object.
For better understanding, press F12 to open the Inspect Element of your browser, and go to the console to write the following commands:
var response = '{"result":true,"count":1}'; // Sample JSON object (string form)
JSON.parse(response); // Converts passed string to a JSON object.
Now run the command:
console.log(JSON.parse(response));
You'll get output as Object {result: true, count: 1}.
In order to use that object, you can assign it to the variable, let's say obj:
var obj = JSON.parse(response);
Now by using obj and the dot(.) operator you can access properties of the JSON Object.
Try to run the command
console.log(obj.result);
Without using a library you can use eval - the only time you should use. It's safer to use a library though.
eg...
var response = '{"result":true , "count":1}';
var parsedJSON = eval('('+response+')');
var result=parsedJSON.result;
var count=parsedJSON.count;
alert('result:'+result+' count:'+count);
If you like
var response = '{"result":true,"count":1}';
var JsonObject= JSON.parse(response);
you can access the JSON elements by JsonObject with (.) dot:
JsonObject.result;
JsonObject.count;
I thought JSON.parse(myObject) would work. But depending on the browsers, it might be worth using eval('('+myObject+')'). The only issue I can recommend watching out for is the multi-level list in JSON.
An easy way to do it:
var data = '{"result":true,"count":1}';
var json = eval("[" +data+ "]")[0]; // ;)
If you use Dojo Toolkit:
require(["dojo/json"], function(JSON){
JSON.parse('{"hello":"world"}', true);
});
As mentioned by numerous others, most browsers support JSON.parse and JSON.stringify.
Now, I'd also like to add that if you are using AngularJS (which I highly recommend), then it also provides the functionality that you require:
var myJson = '{"result": true, "count": 1}';
var obj = angular.fromJson(myJson);//equivalent to JSON.parse(myJson)
var backToJson = angular.toJson(obj);//equivalent to JSON.stringify(obj)
I just wanted to add the stuff about AngularJS to provide another option. NOTE that AngularJS doesn't officially support Internet Explorer 8 (and older versions, for that matter), though through experience most of the stuff seems to work pretty well.
If you use jQuery, it is simple:
var response = '{"result":true,"count":1}';
var obj = $.parseJSON(response);
alert(obj.result); //true
alert(obj.count); //1
This question already has answers here:
Safely turning a JSON string into an object
(28 answers)
Closed 7 years ago.
I want to parse a JSON string in JavaScript. The response is something like
var response = '{"result":true,"count":1}';
How can I get the values result and count from this?
The standard way to parse JSON in JavaScript is JSON.parse()
The JSON API was introduced with ES5 (2011) and has since been implemented in >99% of browsers by market share, and Node.js. Its usage is simple:
const json = '{ "fruit": "pineapple", "fingers": 10 }';
const obj = JSON.parse(json);
console.log(obj.fruit, obj.fingers);
The only time you won't be able to use JSON.parse() is if you are programming for an ancient browser, such as IE 7 (2006), IE 6 (2001), Firefox 3 (2008), Safari 3.x (2009), etc. Alternatively, you may be in an esoteric JavaScript environment that doesn't include the standard APIs. In these cases, use json2.js, the reference implementation of JSON written by Douglas Crockford, the inventor of JSON. That library will provide an implementation of JSON.parse().
When processing extremely large JSON files, JSON.parse() may choke because of its synchronous nature and design. To resolve this, the JSON website recommends third-party libraries such as Oboe.js and clarinet, which provide streaming JSON parsing.
jQuery once had a $.parseJSON() function, but it was deprecated with jQuery 3.0. In any case, for a long time, it was nothing more than a wrapper around JSON.parse().
WARNING!
This answer stems from an ancient era of JavaScript programming during which there was no builtin way to parse JSON. The advice given here is no longer applicable and probably dangerous. From a modern perspective, parsing JSON by involving jQuery or calling eval() is nonsense. Unless you need to support IE 7 or Firefox 3.0, the correct way to parse JSON is JSON.parse().
First of all, you have to make sure that the JSON code is valid.
After that, I would recommend using a JavaScript library such as jQuery or Prototype if you can because these things are handled well in those libraries.
On the other hand, if you don't want to use a library and you can vouch for the validity of the JSON object, I would simply wrap the string in an anonymous function and use the eval function.
This is not recommended if you are getting the JSON object from another source that isn't absolutely trusted because the eval function allows for renegade code if you will.
Here is an example of using the eval function:
var strJSON = '{"result":true,"count":1}';
var objJSON = eval("(function(){return " + strJSON + ";})()");
alert(objJSON.result);
alert(objJSON.count);
If you control what browser is being used or you are not worried people with an older browser, you can always use the JSON.parse method.
This is really the ideal solution for the future.
If you are getting this from an outside site it might be helpful to use jQuery's getJSON. If it's a list you can iterate through it with $.each
$.getJSON(url, function (json) {
alert(json.result);
$.each(json.list, function (i, fb) {
alert(fb.result);
});
});
If you want to use JSON 3 for older browsers, you can load it conditionally with:
<script>
window.JSON ||
document.write('<script src="//cdnjs.cloudflare.com/ajax/libs/json3/3.2.4/json3.min.js"><\/scr'+'ipt>');
</script>
Now the standard window.JSON object is available to you no matter what browser a client is running.
The following example will make it clear:
let contactJSON = '{"name":"John Doe","age":"11"}';
let contact = JSON.parse(contactJSON);
console.log(contact.name + ", " + contact.age);
// Output: John Doe, 11
If you pass a string variable (a well-formed JSON string) to JSON.parse from MVC #Viewbag that has doublequote, '"', as quotes, you need to process it before JSON.parse (jsonstring)
var jsonstring = '#ViewBag.jsonstring';
jsonstring = jsonstring.replace(/"/g, '"');
You can either use the eval function as in some other answers. (Don't forget the extra braces.) You will know why when you dig deeper), or simply use the jQuery function parseJSON:
var response = '{"result":true , "count":1}';
var parsedJSON = $.parseJSON(response);
OR
You can use this below code.
var response = '{"result":true , "count":1}';
var jsonObject = JSON.parse(response);
And you can access the fields using jsonObject.result and jsonObject.count.
Update:
If your output is undefined then you need to follow THIS answer. Maybe your json string has an array format. You need to access the json object properties like this
var response = '[{"result":true , "count":1}]'; // <~ Array with [] tag
var jsonObject = JSON.parse(response);
console.log(jsonObject[0].result); //Output true
console.log(jsonObject[0].count); //Output 1
The easiest way using parse() method:
var response = '{"a":true,"b":1}';
var JsonObject= JSON.parse(response);
this is an example of how to get values:
var myResponseResult = JsonObject.a;
var myResponseCount = JsonObject.b;
JSON.parse() converts any JSON String passed into the function, to a JSON object.
For better understanding, press F12 to open the Inspect Element of your browser, and go to the console to write the following commands:
var response = '{"result":true,"count":1}'; // Sample JSON object (string form)
JSON.parse(response); // Converts passed string to a JSON object.
Now run the command:
console.log(JSON.parse(response));
You'll get output as Object {result: true, count: 1}.
In order to use that object, you can assign it to the variable, let's say obj:
var obj = JSON.parse(response);
Now by using obj and the dot(.) operator you can access properties of the JSON Object.
Try to run the command
console.log(obj.result);
Without using a library you can use eval - the only time you should use. It's safer to use a library though.
eg...
var response = '{"result":true , "count":1}';
var parsedJSON = eval('('+response+')');
var result=parsedJSON.result;
var count=parsedJSON.count;
alert('result:'+result+' count:'+count);
If you like
var response = '{"result":true,"count":1}';
var JsonObject= JSON.parse(response);
you can access the JSON elements by JsonObject with (.) dot:
JsonObject.result;
JsonObject.count;
I thought JSON.parse(myObject) would work. But depending on the browsers, it might be worth using eval('('+myObject+')'). The only issue I can recommend watching out for is the multi-level list in JSON.
An easy way to do it:
var data = '{"result":true,"count":1}';
var json = eval("[" +data+ "]")[0]; // ;)
If you use Dojo Toolkit:
require(["dojo/json"], function(JSON){
JSON.parse('{"hello":"world"}', true);
});
As mentioned by numerous others, most browsers support JSON.parse and JSON.stringify.
Now, I'd also like to add that if you are using AngularJS (which I highly recommend), then it also provides the functionality that you require:
var myJson = '{"result": true, "count": 1}';
var obj = angular.fromJson(myJson);//equivalent to JSON.parse(myJson)
var backToJson = angular.toJson(obj);//equivalent to JSON.stringify(obj)
I just wanted to add the stuff about AngularJS to provide another option. NOTE that AngularJS doesn't officially support Internet Explorer 8 (and older versions, for that matter), though through experience most of the stuff seems to work pretty well.
If you use jQuery, it is simple:
var response = '{"result":true,"count":1}';
var obj = $.parseJSON(response);
alert(obj.result); //true
alert(obj.count); //1
I know this isn't the best way to do it, but I have no other choice :(
I have to access the items in JSONObject by their index. The standard way to access objects is to just wirte this[objectName] or this.objectName. I also found a method to get all the fields inside a json object:
(for (var key in p) {
if (p.hasOwnProperty(key)) {
alert(key + " -> " + p[key]);
}
}
(Soruce : Loop through Json object).
However there is no way of accessing the JSONfields directly by a index. The only way I see right now, is to create an array, with the function above, get the fieldname by index and then get the value by fieldname.
As far as I see it, the p (in our case the JSON file must be an iteratable array to, or else the foreach loop wouldn't work. How can I access this array directly? Or is it some kind of unsorted list?
A JSON Object is more like a key-value-map; so, yes, it is unsorted. The only way to get around is the index->property name map you've already mentioned:
var keysbyindex = Object.keys(object);
for (var i=0; i<keysbyindex.length; i++)
alert(object[keysbyindex[i]]);
But why would you need these indexes? A unsorted map also has no length property, as an Array had. Why don't you use the for-in-loop
var counter = 0; // if you need it
for (var key in object) {
alert(object[key])
counter++;
}
? If you have a parsed JSON object, i.e. a plain JS Object, you won't have to worry about enumerable prototype properties.
Based on Bergis anserwer this is my solution:
var keysbyindex = Object.keys(this);
alert(this[keysbyindex[index]]);
return this[keysbyindex[index] || ""];
However, I think (not tested) it's extremly bad regaring performace and shouldn't be used! But desperate times require desperate measures.....
I don't think you can actually achieve this without creating your own parsing of JSON. You're writing that you want to go trough a JSON-object, but what you're actually trying to do is go trough a plain old Javascript object. Json is simply a string-representation used to transfer/store said object, and in here lies the main problem: the parser that transforms the string into an actual object (ie. the browser in most cases) can chose to ignore the order it finds the properties if it want to. Also, different browsers might have different approaches to parsing JSON for all you know. If they simply use a hash-map for the object that it's simple to loop through it, but the order won't be dependent on the order of the keys in the file, but rather the keys themselves.
For example, if you have the json {"b":"b","a":"a"} and do the for in loop, under some implementations you might end up with a comming first, and in others you might end up with b.
var jsn = {keyName: 'key value result come here...'};
var arr = jsn ? $.map(jsn, function (el) { return el }) : [0];
console.log(arr[0])
$('.result').text(arr[0]);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<span class="result"></span>
'[{"SponsorID":382,"SponsorName":"Test Name","MonthEndReport":true,"AccountingManager":"Me","UnboundProperties":[],"State":16}]'
When I try to access the above like this:
for (var i = 0; i < data.length; i++) {
alert(data[i]);
}
It spells out each thing, such as [, {, ", S, and etc.
I also tried doing data[i].SponsorName but obviously got undefined. How should I be accessing this?
You need to parse the JSON string, preferably with JSON.parse. The JSON API is built into more modern browsers and can be provided to older browsers by including Crockford's JSON script. Crockford's script will detect if the browser already provides the API and adds it if not.
With that in place, if your JSON is in a string variable named response, you can:
var parsedResponse = JSON.parse( response );
//run your iterating code on parsedResponse
You would first need to eval() or more ideally JSON.parse() the JSON string in to a Javascript object. This assumes you trust the source of the JSON.
var jsonobj = JSON.parse(data);
// Now view the object's structure
console.dir(jsonobj);
Here's what it looks like after being evaluated and printed out:
var array = JSON.parse('[{"SponsorID":382,"SponsorName":"Test Name","MonthEndReport":true,"AccountingManager":"Me","UnboundProperties":[],"State":16}]')
array[0].AccountingManager; // "me"
Or everyone's favorite library, since IE7 and below don't have native support:
$.parseJSON('[{"SponsorID":382,"SponsorName":"Test Name","MonthEndReport":true,"AccountingManager":"Me","UnboundProperties":[],"State":16}]')
You parsed the Json string first, right?
var data = '[{"SponsorID":382,"SponsorName":"Test Name","MonthEndReport":true,"AccountingManager":"Me","UnboundProperties":[],"State":16}]';
data = JSON.parse(data);
alert(data.SponsorName);
JSON.parse, when available, is the preferred method over "eval" because of security and performance issues.
You've got a JSON array followed by an object:
var data = [{"SponsorID":382,"SponsorName":"Test Name","MonthEndReport":true,"AccountingManager":"Me","UnboundProperties":[],"State":16}];
alert(data[0].SponsorID);
I have a javascript array object like
{arr = {"0":{"name":"henry","role":"user"},"1":{"name":"mark","role":"admin"}}
I have a html which requests this array from my server( by including a script tag with url to my server function that serves this array}
The problem is that When I run my HTML file in firefox, it easily detects this array and does the further processing with it but On IE , when I try to access the elements of the array, it throws an exception (object is null or undefined).
Any idea why element detection could be failing in IE.
How do we find out the properties of an array object in IE?
That is not really an array, is simply an object literal with numeric properties, you should iterate it by using the for...in statement:
var arr = {"0":{"name":"henry","role":"user"},
"1":{"name":"mark","role":"admin"}};
for (var key in arr) {
if (arr.hasOwnProperty(key)) {
// value = arr[key];
}
}
But I think you should simply return a real Array:
var arr = [{"name":"henry","role":"user"},
{"name":"mark","role":"admin"}];