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Issue loading data into a dropdown via ajax

Encountering an issue loading a dropdown dynamically using JQuery AJAX.
The php is returning a valid JSON response. But when I attempt to load the data, I'm getting back either undefined, [object Object] or a single option with all my values comma separated. Nothing I've tried yields the correct answer.
This is the AJAX code block:
$.ajax({
type: "GET",
url:"data/getdata_codes.php",
dataType: "json",
success: function (data) {
alert("Success section");
alert(data);
$.each(data,function(key,value) <--Fails here
{
alert(key);
alert(value);
var option="<option value="+key+">"+value+"</option>";
alert(option);
$(option).appendTo('#myList');
});
},
error: function(xhr) {
alert("An error occured: "+ xhr.status + " " + xhr.statusText);
}
});
This is the JSON which is returned from the PHP, it validates.
{"data":[[{"0":"-1","CODE":"-1"}],
[{"0":"0","CODE":"0"}],
[{"0":"12","CODE":"12"}],
[{"0":"213","CODE":"213"}],
[{"0":"357","CODE":"357"}],
[{"0":"364","CODE":"364"}],
[{"0":"501","CODE":"501"}],
[{"0":"661","CODE":"661"}]]}

First of all your array is filled with arrays with 1 object. That makes it overly complicated.
Try something like this:
$(data.data).each(function(index, element) <- I guess your data variable also has a data attribute?
{
var array = element;
var objectInArray = array[0];
var key = objectInArray.0;
var value = objectInArray.CODE;
alert(key);
alert(value);
var option="<option value="+key+">"+value+"</option>";
alert(option);
$(option).appendTo('#myList');
});

Uncaught TypeError: Cannot read property 'results' of undefined

I'm a complete newby to JS. Trying to use SharePoint REST API to display a link list in a footer. Keep getting this error no matter what I do. It is for this line LoadFooterLinks(results.d.results);
function GetFooterLinks() {
var url = _spPageContextInfo.siteAbsoluteUrl + "/_api/lists/getbytitle('Footer Links')/items/?$orderby=Display_x0020_on_x0020_Homepage";
$.ajax({
url: url,
type: "GET",
headers: {
"accept": "application/json;odata=verbose",
},
success: function (results) {
LoadFooterLinks(results.d.results);
},
error: function (error) {
console.log("Error in getting List: " + listName);
}
});
}

A few things:
How do you know you have an "error"?
Is is a Javascript Exception?
WHAT IS the error or Exception?
How do you know the error isn't with your LoadFooterLinks() function?
Most likely your results are NOT what you are expecting. You're obviously:
Successfully making a connection and request
But, you can't be sure what's coming back. It could be:
empty string
null
malformed
Hitting F12 in most browsers will bring up that browser's Developer mode/built-in JS console
My code changes below should help you debug by outputting to the console for you.
Things to NOTE about the code changes:
The difference between:
catching a JavaScript runtime exception/error using try-catch vs.
outputting the string variable arbitrarily named "error" in the failure callback method of the $.ajax object
Print an exception to to the console doesn't require console.err()
If you want to show a string as an error in the console use console.err(), not console.log.
Null is an object, not a datatype or primitive like the other ones in JavaScript. For Example,
boolean
string
undefined
number
New Code
function GetFooterLinks() {
var url = _spPageContextInfo.siteAbsoluteUrl +
"/_api/lists/getbytitle('Footer Links')/items/?
$orderby=Display_x0020_on_x0020_Homepage"
;
$.ajax({
url: url,
type: "GET",
headers: {
"accept": "application/json;odata=verbose",
},
success: function (results) {
if (!results) { // should handle null and empty strings
try{
LoadFooterLinks(results.d.results);
}
catch (e){ // catch any JavaScript runtime exception (error)
console.log(e); // print the error to the console
// (hit F12 in most browsers to see
// the console BEFORE you refresh
// the page to run your code)
}
}
else {
var msg = "The 'results' variable is ";
var varType = typeof(results);
if (varType == "object") {
msg += "NULL";
}
else {
msg += varType;
}
}
},
error: function (error) {
// this 'error' variable can be named
// anything you'd like and is a string
// description of the AJAX error.
// This description comes from $.ajax -
// which is part of jQuery (a JS library).
// This "error" is not a native JS
// exception; therefore, you wouldn't
// use a TRY-CATCH. Also, since it's
// only a string, if you want to show it
// as an error in the console, you should
// use `console.err`, not `console.log`.
console.err("Error in getting List: (0)", error);
}
});
}

What you are basically doing is making a request to the "/_api/lists/getbytitle" method.
When that method returns a response, it will do so as an object named "results", as you can see under the "success" callback.
What you are doing afterwards is reading a property called "d" and within "d" you are trying to obtain the value of property called "results".
What the error is saying is that "d" is undefined therefore it cannot retrieve the value of "results" from "d".
I suggest you check what is inside the object "results" of the success callback.

For SharePoint API result, you would need to parse the JSON response to convert it to Javascript object. I've modified your code a bit to make it work in this case.
function GetFooterLinks() {
var url = _spPageContextInfo.siteAbsoluteUrl + "/_api/lists/getbytitle('Footer Links')/items/?$orderby=Display_x0020_on_x0020_Homepage";
$.ajax({
url: url,
type: "GET",
headers: {
"accept": "application/json;odata=verbose",
},
success: function (response) {
var svcData = JSON.parse(response.data).d.results;
LoadFooterLinks(svcData);
},
error: function (error) {
console.log("Error in getting List: " + listName);
}
});
}

How to check if ajax response is javascript content type?

I have several different forms that each return something different. I need to detect if it's a simple string (so i can put it in the error/status area) or if its javascript I do nothing and let it execute.
This is currently how I'm doing my checking, but I want to make sure this is 100% sturdy and reliable... I couldn't think of any other way.
The other option would be to always use JSON, but then I need a JSON shim, as well as somehow trying to serialize javascript into JSON.
$.ajax({
type: 'POST',
url: form.attr('action'),
data: form.serialize()
})
.done(function(data, textStatus, xhr) {
if (!xhr.getResponseHeader('Content-Type').match(/text\/javascript/i)) {
form.find('.status').text(data).removeClass().addClass('status status-done').slideDown(200);
} else {
// this is where i do nothing and let JS run
}
})
The following works, but I'm afraid there would be some edge case where it's not going to work (not sure what that might be, but it's important this section works 100%)

Note, Not certain about detail of requirement . If interpret Question correctly , at different form elements , different response types from $.ajax() requests ? a) Check for response type string ? b) do nothing ?
Could possibly check for response type string within json response with
if (typeof data.data === "string") {
// do stuff , with `string`
}
if $.ajax() expect json response , receive js , could possible run the piece immediately. At piece below , first response is string , filtered through if at .done() . Second response json object having a js function expression as property , which appear to run immediately , at $.ajax() success textStatus . Still capable to check response type of object at else , though , run as script . See empty xhr.repsonseText and xhr.reponseJSON at console
Try
var urls = [["/echo/json/","abc"]
, ["/echo/json/",
{"abc":
(function() {
setTimeout(function() {
$("body").append("<div id=data>"
+ "object" + "</div>");
$("#data")
.hide(0)
.fadeIn(1200)},1200)
}())
}]
];
var request = function(url, _data) {
$.ajax({
type: 'POST',
url: url,
data: {json : JSON.stringify({"data":_data})}
})
.done(function(data, textStatus, xhr) {
if (typeof data.data === "string") {
$("body").append("<div>" + data.data + "</div>")
} else {
console.log(typeof data.data
, data
, xhr.responseText
, xhr.responseJSON);
// this is where i do nothing and let JS run
}
})
};
$.each(urls, function(k, v) {
request(v[0], v[1])
});
jsfiddle http://jsfiddle.net/guest271314/y9b7t740/
See
jQuery getScript() vs document.createElement('script') , script.js
Calling a JavaScript function returned from an Ajax response
jQuery: Evaluate script in ajax response
What is JSONP all about?

jQuery ajax returned data: json and html mix?

I have this ajax request to get the data from my server, and the dataType is always html by default. But sometimes it would return json from the server, so I want to check if the returned data is html then execute A else execute B. Is it possible?
My jquery,
$.ajax({
type: "GET",
dataType: "html",
url: request_url,
context: $('#meat'),
async: true,
beforeSend: function () {},
success: function (returndata, status, jqXHR) {
if ($.parseJSON(returndata) === false) A;
else B.
}
});
I get this error when the returned data is html,
SyntaxError: JSON.parse: unexpected character
So how can I make this code versatile?

I'm not sure if there is a better way, but you could try... catch
$.ajax({
type: "GET",
url: request_url,
context: $('#meat'),
async: true,
beforeSend: function() {
},
success: function (returndata, status, jqXHR) {
var parsed;
try
{
parsed = $.parseJSON(returndata);
// Execute B
}
catch(e)
{
// treat as html then
// do parsing here
parsed = returnData;
// Execute A
}
}
});

Essentially, your code is just plain wrong - your serverside API is violating all principles of predictability if the return type can vary in an inconsistent manner. Your code should never have to guess at the type of the returned data.
Having said that, a simple try/catch will help as a workaround for the erratic behaviour if you don't want to fix it. Ie.
try {
if ($.parseJSON(returndata) === false) A;
} catch(e) {
// Treat as HTML here.
}
It's not pretty, but that's what you get for having an unpredictable API that isn't pretty to begin with.

may be you need to handle it like this
try{
var response=jQuery.parseJSON('response from server');
if(typeof response =='object')
{
//control would reach this point if the data is returned as json
}
else
{
//control would reach this point if data is plain text
if(response ===false)
{
//the response was a string "false", parseJSON will convert it to boolean false
}
else
{
//the response was something else
}
}
}
catch(exp){
//controls reaches here, if the data is html
}
Since you need to check the html data as well, you may need to take care of this,
Might also need to use a try / catch for exceptions if it is possible that parseJSON is going to be dealing with something other than JSON values (i.e. HTML)
REF:How can I check if a value is a json object?
EDIT:Edited to make code more precise towards solution

jQuery returning "parsererror" for ajax request

Been getting a "parsererror" from jquery for an Ajax request, I have tried changing the POST to a GET, returning the data in a few different ways (creating classes, etc.) but I cant seem to figure out what the problem is.
My project is in MVC3 and I'm using jQuery 1.5
I have a Dropdown and on the onchange event I fire off a call to get some data based on what was selected.
Dropdown: (this loads the "Views" from the list in the Viewbag and firing the event works fine)
#{
var viewHtmls = new Dictionary<string, object>();
viewHtmls.Add("data-bind", "value: ViewID");
viewHtmls.Add("onchange", "javascript:PageModel.LoadViewContentNames()");
}
#Html.DropDownList("view", (List<SelectListItem>)ViewBag.Views, viewHtmls)
Javascript:
this.LoadViewContentNames = function () {
$.ajax({
url: '/Admin/Ajax/GetViewContentNames',
type: 'POST',
dataType: 'json',
data: { viewID: $("#view").val() },
success: function (data) {
alert(data);
},
error: function (data) {
debugger;
alert("Error");
}
});
};
The above code successfully calls the MVC method and returns:
[{"ViewContentID":1,"Name":"TopContent","Note":"Content on the top"},
{"ViewContentID":2,"Name":"BottomContent","Note":"Content on the bottom"}]
But jquery fires the error event for the $.ajax() method saying "parsererror".

I recently encountered this problem and stumbled upon this question.
I resolved it with a much easier way.
Method One
You can either remove the dataType: 'json' property from the object literal...
Method Two
Or you can do what #Sagiv was saying by returning your data as Json.
The reason why this parsererror message occurs is that when you simply return a string or another value, it is not really Json, so the parser fails when parsing it.
So if you remove the dataType: json property, it will not try to parse it as Json.
With the other method if you make sure to return your data as Json, the parser will know how to handle it properly.

See the answer by #david-east for the correct way to handle the issue
This answer is only relevant to a bug with jQuery 1.5 when using the file: protocol.
I had a similar problem recently when upgrading to jQuery 1.5. Despite getting a correct response the error handler fired. I resolved it by using the complete event and then checking the status value. e.g:
complete: function (xhr, status) {
if (status === 'error' || !xhr.responseText) {
handleError();
}
else {
var data = xhr.responseText;
//...
}
}

You have specified the ajax call response dataType as:
'json'
where as the actual ajax response is not a valid JSON and as a result the JSON parser is throwing an error.
The best approach that I would recommend is to change the dataType to:
'text'
and within the success callback validate whether a valid JSON is being returned or not, and if JSON validation fails, alert it on the screen so that its obvious for what purpose the ajax call is actually failing. Have a look at this:
$.ajax({
url: '/Admin/Ajax/GetViewContentNames',
type: 'POST',
dataType: 'text',
data: {viewID: $("#view").val()},
success: function (data) {
try {
var output = JSON.parse(data);
alert(output);
} catch (e) {
alert("Output is not valid JSON: " + data);
}
}, error: function (request, error) {
alert("AJAX Call Error: " + error);
}
});

the problem is that your controller returning string or other object that can't be parsed.
the ajax call expected to get Json in return. try to return JsonResult in the controller like that:
public JsonResult YourAction()
{
...return Json(YourReturnObject);
}
hope it helps :)

There are lots of suggestions to remove
dataType: "json"
While I grant that this works it's ignoring the underlying issue. If you're confident the return string really is JSON then look for errant whitespace at the start of the response. Consider having a look at it in fiddler. Mine looked like this:
Connection: Keep-Alive
Content-Type: application/json; charset=utf-8
{"type":"scan","data":{"image":".\/output\/ou...
In my case this was a problem with PHP spewing out unwanted characters (in this case UTF file BOMs). Once I removed these it fixed the problem while also keeping
dataType: json

Your JSON data might be wrong. http://jsonformatter.curiousconcept.com/ to validate it.

Make sure that you remove any debug code or anything else that might be outputting unintended information. Somewhat obvious, but easy to forgot in the moment.

I don't know if this is still actual but problem was with Encoding. Changing to ANSI resolved the problem for me.

If you get this problem using HTTP GET in IE I solved this issue by setting the cache: false.
As I used the same url for both HTML and json requests it hit the cache instead of doing a json call.
$.ajax({
url: '/Test/Something/',
type: 'GET',
dataType: 'json',
cache: false,
data: { viewID: $("#view").val() },
success: function (data) {
alert(data);
},
error: function (data) {
debugger;
alert("Error");
}
});

you should remove the dataType: "json". Then see the magic... the reason of doing such thing is that you are converting json object to simple string.. so json parser is not able to parse that string due to not being a json object.
this.LoadViewContentNames = function () {
$.ajax({
url: '/Admin/Ajax/GetViewContentNames',
type: 'POST',
data: { viewID: $("#view").val() },
success: function (data) {
alert(data);
},
error: function (data) {
debugger;
alert("Error");
}
});
};

incase of Get operation from web .net mvc/api, make sure you are allow get
return Json(data,JsonRequestBehavior.AllowGet);

If you don't want to remove/change dataType: json, you can override jQuery's strict parsing by defining a custom converter:
$.ajax({
// We're expecting a JSON response...
dataType: 'json',
// ...but we need to override jQuery's strict JSON parsing
converters: {
'text json': function(result) {
try {
// First try to use native browser parsing
if (typeof JSON === 'object' && typeof JSON.parse === 'function') {
return JSON.parse(result);
} else {
// Fallback to jQuery's parser
return $.parseJSON(result);
}
} catch (e) {
// Whatever you want as your alternative behavior, goes here.
// In this example, we send a warning to the console and return
// an empty JS object.
console.log("Warning: Could not parse expected JSON response.");
return {};
}
}
},
...
Using this, you can customize the behavior when the response cannot be parsed as JSON (even if you get an empty response body!)
With this custom converter, .done()/success will be triggered as long as the request was otherwise successful (1xx or 2xx response code).

I was also getting "Request return with error:parsererror." in the javascript console.
In my case it wasn´t a matter of Json, but I had to pass to the view text area a valid encoding.
String encodedString = getEncodedString(text, encoding);
view.setTextAreaContent(encodedString);

I have encountered such error but after modifying my response before sending it to the client it worked fine.
//Server side
response = JSON.stringify('{"status": {"code": 200},"result": '+ JSON.stringify(result)+'}');
res.send(response); // Sending to client
//Client side
success: function(res, status) {
response = JSON.parse(res); // Getting as expected
//Do something
}

I had the same problem, turned out my web.config was not the same with my teammates.
So please check your web.config.
Hope this helps someone.

I ran into the same issue. What I found to solve my issue was to make sure to use double quotes instead of single quotes.
echo "{'error':'Sorry, your file is too large. (Keep it under 2MB)'}";
-to-
echo '{"error":"Sorry, your file is too large. (Keep it under 2MB)"}';

The problem
window.JSON.parse raises an error in $.parseJSON function.
<pre>
$.parseJSON: function( data ) {
...
// Attempt to parse using the native JSON parser first
if ( window.JSON && window.JSON.parse ) {
return window.JSON.parse( data );
}
...
</pre>
My solution
Overloading JQuery using requirejs tool.
<pre>
define(['jquery', 'jquery.overload'], function() {
//Loading jquery.overload
});
</pre>
jquery.overload.js file content
<pre>
define(['jquery'],function ($) {
$.parseJSON: function( data ) {
// Attempt to parse using the native JSON parser first
/** THIS RAISES Parsing ERROR
if ( window.JSON && window.JSON.parse ) {
return window.JSON.parse( data );
}
**/
if ( data === null ) {
return data;
}
if ( typeof data === "string" ) {
// Make sure leading/trailing whitespace is removed (IE can't handle it)
data = $.trim( data );
if ( data ) {
// Make sure the incoming data is actual JSON
// Logic borrowed from http://json.org/json2.js
if ( rvalidchars.test( data.replace( rvalidescape, "#" )
.replace( rvalidtokens, "]" )
.replace( rvalidbraces, "")) ) {
return ( new Function( "return " + data ) )();
}
}
}
$.error( "Invalid JSON: " + data );
}
return $;
});
</pre>