Develop Reference

How to retrieve JSON data located in a different file

I have 6 json files in the same directory as my index.htm. Each json structure has saved game data in it. I want to let the user choose a file and load its associated json data structure. How can I go about retrieving that data?
I tried using
var myjson = new Object();
$.getJSON("myJSON.json", function(json) {
myjson = JSON.stringify(json);
console.log(myjson);
});
This gives me an XMLHttpRequest error (cross-origin request not supported).

Your execution is fine -- though like the comments on your post suggest, you need to change the protocol you're using. Really just load the HTML page using http://127.0.0.1/mypage.html instead of file://home/website/mypage.html and you can likely keep your javascript the same.
Aside from this, you might want to consider the data in your myJSON.json file. I noticed if the JSON data contains function definitions then it will cause $.ajax() or in this case $.getJSON() to throw a parse error.
So this will not work
{
"json" : function () {
alert("HI");
},
"hello" : 432
}
But this will work
{
"json" : "5",
"hello" : 432
}

JSON Reader issue: cannot access jsonData

I have a strange thing going on here: I am using a JSON reader within a store to fetch search results. After loading the store I receive data or error states (built together as a JSON, too). So in both ways I get a successfully response, so I have to check the JSON for myself to trap "error conditions". But I cannot access the jsonData property that shhould be a JSON object within the reader. Chrome tells me that:
I can access the applyDefaults though (it returns true in that case) but not the jsonData.
My code looks like this:
var result = searchStore.getProxy().getReader();
console.log(result.jsonData);
The output is "undefined". As you can see in the picture the jsonData object holds my JSON (with the isError property I wanted to access).
What I am doing wrong?

You need to think more async and think of the timing it takes for a request to return and when you are trying to get the jsonData. Instead of using console.log, set a breakpoint or use the debugger; statement so you can freeze the browser and walk through the code. You can then inspect variables and such to see what the object looks like.

Try to access your JSON data in a success callback, to make sure the data is gathered from the server.

Someone please tell me what is wrong with my $.parseJSON [javascript / jquery]

Here is my tested result. I run my app, I get the "Hello" alert. But I don't get "After parse JSON" alert.
When I comment out the var rstList = $.parseJSON(data); line, "After parse JSON" alert prompted correctly.
I have check many document and reference but couldn't find out what is wrong with my $.parseJSON(). Please advice, thank you.
//Show restaurant listing
$('#restaurantList').on("pagebeforecreate", function() {
$.getJSON("http://mydomain/api/restaurant", function( data ) {
alert('Hello');
var rstList = $.parseJSON(data);
alert('After parse JSON');
});
});

Contrary to what the name implies, $.getJSON doesn't give you some JSON but the result of the parsing.
From the documentation :
The success callback is passed the returned data, which is typically a
JavaScript object or array as defined by the JSON structure and parsed
using the $.parseJSON() method.
You data is already parsed, don't parse it.
BTW, as Niet commented, you should have looked at the console to have a little more information on the error halting your script's execution. See Using the console.

Because you are trying to parse a json object again. Which causes the error. $.getJSON
will return the json object. You dont need to parse it again

I keep getting "Uncaught SyntaxError: Unexpected token o"

I'm trying to learn some html/css/javascript, so I'm writing myself a teaching project.
The idea was to have some vocabulary contained in a json file which would then be loaded into a table. I managed to load the file in and print out one of its values, after which I began writing the code to load the values into the table.
After doing that I started getting an error, so I removed all the code I had written, leaving me with only one line (the same line that had worked before) ... only the error is still there.
The error is as follows:
Uncaught SyntaxError: Unexpected token o
(anonymous function)script.js:10
jQuery.Callbacks.firejquery-1.7.js:1064
jQuery.Callbacks.self.fireWithjquery-1.7.js:1182
donejquery-1.7.js:7454
jQuery.ajaxTransport.send.callback
My javascript code is contained in a separate file and is simply this:
function loadPageIntoDiv(){
document.getElementById("wokabWeeks").style.display = "block";
}
function loadWokab(){
//also tried getJSON which threw the same error
jQuery.get('wokab.json', function(data) {
var glacier = JSON.parse(data);
});
}
And my JSON file just has the following right now:
[
{
"english": "bag",
"kana": "kaban",
"kanji": "K"
},
{
"english": "glasses",
"kana": "megane",
"kanji": "M"
}
]
Now the error is reported in line 11 which is the var glacier = JSON.parse(data); line.
When I remove the json file I get the error: "GET http://.../wokab.json 404 (Not Found)" so I know it's loading it (or at least trying to).

Looks like jQuery takes a guess about the datatype. It does the JSON parsing even though you're not calling getJSON()-- then when you try to call JSON.parse() on an object, you're getting the error.
Further explanation can be found in Aditya Mittal's answer.

The problem is very simple
jQuery.get('wokab.json', function(data) {
var glacier = JSON.parse(data);
});
You're parsing it twice. get uses the dataType='json', so data is already in json format.
Use $.ajax({ dataType: 'json' ... to specifically set the returned data type!

Basically if the response header is text/html you need to parse, and if the response header is application/json it is already parsed for you.
Parsed data from jquery success handler for text/html response:
var parsed = JSON.parse(data);
Parsed data from jquery success handler for application/json response:
var parsed = data;

Another hints for Unexpected token errors.
There are two major differences between javascript objects and json:
json data must be always quoted with double quotes.
keys must be quoted
Correct JSON
{
"english": "bag",
"kana": "kaban",
"kanji": "K"
}
Error JSON 1
{
'english': 'bag',
'kana': 'kaban',
'kanji': 'K'
}
Error JSON 2
{
english: "bag",
kana: "kaban",
kanji: "K"
}
Remark
This is not a direct answer for that question. But it's an answer for Unexpected token errors. So it may be help others who stumple upon that question.

Simply the response is already parsed, you don't need to parse it again. if you parse it again it will give you "unexpected token o" however you have to specify datatype in your request to be of type dataType='json'

I had a similar problem just now and my solution might help. I'm using an iframe to upload and convert an xml file to json and send it back behind the scenes, and Chrome was adding some garbage to the incoming data that only would show up intermittently and cause the "Uncaught SyntaxError: Unexpected token o" error.
I was accessing the iframe data like this:
$('#load-file-iframe').contents().text()
which worked fine on localhost, but when I uploaded it to the server it stopped working only with some files and only when loading the files in a certain order. I don't really know what caused it, but this fixed it. I changed the line above to
$('#load-file-iframe').contents().find('body').text()
once I noticed some garbage in the HTML response.
Long story short check your raw HTML response data and you might turn something up.

SyntaxError: Unexpected token o in JSON
This also happens when you forget to use the await keyword for a method that returns JSON data.
For example:
async function returnJSONData()
{
return "{\"prop\": 2}";
}
var json_str = returnJSONData();
var json_obj = JSON.parse(json_str);
will throw an error because of the missing await. What is actually returned is a Promise [object], not a string.
To fix just add await as you're supposed to:
var json_str = await returnJSONData();
This should be pretty obvious, but the error is called on JSON.parse, so it's easy to miss if there's some distance between your await method call and the JSON.parse call.

Make sure your JSON file does not have any trailing characters before or after. Maybe an unprintable one? You may want to try this way:
[{"english":"bag","kana":"kaban","kanji":"K"},{"english":"glasses","kana":"megane","kanji":"M"}]

const getCircularReplacer = () => {
const seen = new WeakSet();
return (key, value) => {
if (typeof value === "object" && value !== null) {
if (seen.has(value)) {
return;
}
seen.add(value);
}
return value;
};
};
JSON.stringify(tempActivity, getCircularReplacer());
Where tempActivity is fething the data which produces the error "SyntaxError: Unexpected token o in JSON at position 1 - Stack Overflow"

Accessing JSON values with a variable

I'm trying to access JSON data with jQuery and grab a specific set of values based on a variable. I've done this before using [] but for some reason I can't figure out what is going wrong this time.
My JSON file (being read in by getJSON, and named jsonmaker.php) looks like this:
{"0107001":{"label":"Canada","x":"0","y":"0.34"},"0107002":{"label":"USA","x":"-0.16","y":"0.53"}}
I then have a function which is essentially this:
function addAttrib(attrib) {
$.getJSON("jsonmaker.php", function(data) {
alert(data[attrib].label);
}
}
But it keeps returning undefined. Any idea what I'm doing wrong? I've checked to make sure the var going to attrib is 0107001, no problems there.
Also, I know my JSON file is a php file so I could filter what's returned to match the attrib value, but I'm looking to develop something that can run purely on HTML and JS, so I could just pack the JSON file for the project and take it with me. No need for a web server w/ PHP etc.

The data access itself works for me:
var data = {"0107001":{"label":"Canada","x":"0","y":"0.34"},"0107002":{"label":"USA","x":"-0.16","y":"0.53"}};
var attrib = "0107002";
alert(data[attrib].label); // USA
Make sure that attrib remains untouched between the moment you call addAttrib() and the moment when the AJAX request completes and your anonymous callback function gets called.
Update: is this your real code? You have at least one syntax error:
function addAttrib(attrib) {
$.getJSON("jsonmaker.php", function(data) {
alert(data[attrib].label);
}); // <- Please note missing ");"
}

In my experience, $.getJSON() doesn't always return an object. Depending on the MIME type that the server returns along with the JSON, you might end up with a string instead of an object. Check what data contains. If it's a string, you must manually parse it using eval() (old style) or JSON.parse() (new browsers only).

try to list all properties from data, to have sure the data is being returned:
for (var p in data){
if (data.hasOwnProperty(p){
alert(data[p]);
}
}
It's not your solution but with this you can know how your data is coming.