$.getJson callback function is not working

Question

I am calling a JSP by passing parameters which outputs a valid JSON as response, but still the $.getJson callback function is not getting fired. JSP page output is

 { "data": [ [ [ 1258185480000,4.39], 
               [ 1258186020000,4.31],
               [ 1258184940000,4.39],
               [ 1258183560000,4.39]  ] ] }

The URL points to the JSP page

My jquery code is

<script id="source" language="javascript" type="text/javascript">
$(function () {   
  alert("before");
  $.getJson(URL,function(json){
            alert("hello");
          var plot = $.plot($("#placeholder"), json.data, options);
    });

 alert("after");
});

Community · Accepted Answer · 2020-06-20 09:12:55Z

11

$.getJSON( URL, function(data) {
  alert("hello");
});

is nothing but a shorthand for ajax call

$.ajax({
  dataType: "json",
  url: URL,
  data: data,
  success: function(data) {
    alert("hello");
  }
});

BUT

Important: As of jQuery 1.4, if the JSON file contains a syntax error, the request will usually fail silently ... For example, all strings represented in JSON, whether they are properties or values, must be enclosed in double-quotes

source: jquery.getjson docs

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Sep 21, 2015 at 8:05

raghavsood33

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1 Comment

Sunding Wei Over a year ago

It makes sense to me: "if the JSON file contains a syntax error, the request will usually fail silently!"

Darin Dimitrov · Accepted Answer · 2009-11-16 08:04:35Z

10

The function is $.getJSON and not $.getJson

answered Nov 16, 2009 at 8:04

Darin Dimitrov

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4 Comments

Santhosh S Over a year ago

I changed to getJSON and tried, still the callback did not get triggered. How to validate json in firebug? I verified in Jsonlint that the response from JSP is a valid JSON

Darin Dimitrov Over a year ago

Is your server sending the correct MIME type: application/json or application/javascript?

Santhosh S Over a year ago

$.ajax({ type: "GET", url: URL, dataType: "json", success: function(results){ alert("Success!"); }, error: function(XMLHttpRequest, textStatus, errorThrown){ alert(textStatus); alert(errorThrown); } }); I get a parse error when I use $.ajax instead of $.getJSON. The data I get back from JSP is { "data": [ [ [ 1258185480000,4.39], [ 1258186020000,4.31], [ 1258184940000,4.39], [ 1258183560000,4.39] ] ] } I have verified that the JSON is proper in jsonlint

Darin Dimitrov Over a year ago

@Santhosh, you need to set the proper Content-Type header in your JSP page. Please verify with FireBug that when you perform the request, the server sends Content-Type: application/json header.

Mark B · Accepted Answer · 2012-12-14 02:12:56Z

3

$.getJSON will not utilize a callback with out a proper JSON object to process.

edited Dec 14, 2012 at 2:12

answered Dec 9, 2012 at 19:24

Mark B

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2 Comments

Arnaud Rinquin Over a year ago

A link to jQuery documentation would highly improve your answer (here it is : api.jquery.com/jQuery.getJSON)

Edward Wagner Over a year ago

This Helped! I am testing in chrome 64.0.3282.167. I was really stuck because chrome was showing the call was made and had all the expected headers and format. Then I saw this comment and thought I should find a linter for json. Sure enough I found jsonlint.com and it shows a failure It took a while to realize I had single quotes. The JSON spec dictates double quotes. With this change $.getJOSN() worked as expected.

sra · Accepted Answer · 2012-01-05 09:47:42Z

2

I just spent about two hours on this. I found another post that discusses the difference between $.getJSON and $.get and how there really isn't any. So I swapped out my getJSON() for get() and it worked.

(Also want to mention that I had also verified everything else was working by logging from the rails action and logging what I could from the javascript outside the callback function.)

edited Jan 5, 2012 at 9:47

sra

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answered Aug 4, 2011 at 14:50

cogline

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2 Comments

Mark Good Over a year ago

I believe the different between $.getJSON and $.get is in the content type (JSON vs XML).

shuva mallick Over a year ago

I am not sure about the difference but $.get did return the JSON object. Thanks guys.

Andy Gaskell · Accepted Answer · 2009-11-16 08:06:06Z

1

Also ensure with Firebug that you are getting valid JSON back from the server.

answered Nov 16, 2009 at 8:06

Andy Gaskell

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3 Comments

Santhosh S Over a year ago

I changed to getJSON and tried, still the callback did not get triggered. How to validate json in firebug? I verified in Jsonlint that the response from JSP is a valid JSON

Andy Gaskell Over a year ago

On the Net tab in Firebug you'll be able to see all of the requests/responses.

Santhosh S Over a year ago

$.ajax( { type: "GET", url: URL, dataType: "json", success: function(results){ alert("Success!"); }, error: function(XMLHttpRequest, textStatus, errorThrown) { alert(textStatus); alert(errorThrown); } }); I get a parse error when I use $.ajax instead of $.getJSON. The data I get back from JSP is { "data": [ [ [ 1258185480000,4.39], [ 1258186020000,4.31], [ 1258184940000,4.39], [ 1258183560000,4.39] ] ] } I have verified that the JSON is proper in jsonlint. How to find what the parse error is ?

Reimond Hill · Accepted Answer · 2019-07-24 09:04:50Z

1

For jQuery 3.4.1:

$.getJSON("test.json", function (json) {
    console.log('Got JSON');
    console.log(json);

})
.fail(function (jqxhr, textStatus, error) {
    var err = textStatus + ", " + error;
    alert("There has been an error. If the problem persists contact the customer service");
})
.always(function () {
    console.log("complete");
});

If you believe that the JSON is ok and you are using chrome try "Empty Cache and Hard Reload".

answered Jul 24, 2019 at 9:04

Reimond Hill

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1 Comment

Skippy le Grand Gourou Over a year ago

Great for debugging, although much more useful with alert(err) rather than the fixed error message.

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