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Javascript - why is this undefined?

The alert at the start shows "undefined", why?
The alerts come in this order:
"success!"
"Data" (what it should be)
"undefined"
I read through multiple threads, the problem was always that ajax was asynchronous, so the data was not defined when it was accessed, but in my case the data is there, the alert in my function shows the data BEFORE the other alert where it is undefined!
Very grateful for any help!
I got this code
var data = getData("");
alert(data); <<<<<<< UNDEFINED
function getData(fileName) {
$.ajax({
async:false,
type: "GET",
url: "breastCancer.csv",
dataType: "text",
success: function (data) {
var arrData = processData(data);
alert("success!");
alert(arrData); <<<<< WORKS GREAT
return arrData;
},
});
}
function processData(data) {
var arrData = CSVToArray(data);
dimensions = arrData[0];
var objects = [];
objects[0] = dimensions;
for (var i = 1; i < arrData.length; i++){
objects[i] = new Object();
for (var j = 0; j < dimensions.length; j++){
objects[i][dimensions[j]] = arrData[i][j];
}
}
return objects;
}
To clarify, I know asynchronous is the way to go for user experience, but this page just has to show data from this call, so its okay for me to wait for it.

Your getData function doesn't return anything.

You need to return it from the function itself.
function getData(fileName) {
$.ajax({
async:false,
type: "GET",
url: "breastCancer.csv",
dataType: "text",
success: function (data) {
var arrData = processData(data);
alert("success!");
alert(arrData); <<<<< WORKS GREAT
return arrData;
},
});
}
^ This returns the data within getData. But getData doesn't do anything with it: such as returning it.
function getData(fileName) {
var ourData = "";
$.ajax({
async:false,
type: "GET",
url: "breastCancer.csv",
dataType: "text",
success: function (data) {
var arrData = processData(data);
ourData = arrData;
},
});
return ourData;
}
This returns the data from getData to whatever calls that function.
edit: also, don't use async:false. Your browser won't capture any events happening until that AJAX completes. The benefit of asynchronous JS is that...we can! And in this case should.

Preface: Don't use async: false. But answering the question:
getData doesn't return anything. You're doing a return from the success callback, but that returns something from the success callback, not getData.
To change it so getData returns something, you'd do this:
function getData(fileName) {
var arrData;
$.ajax({
async:false,
type: "GET",
url: "breastCancer.csv",
dataType: "text",
success: function (data) {
arrData = processData(data);
},
});
return arrData; // <=== Now `getData` returns something
}
But don't do that. Instead, embrace asynchronous programming and remove async: false. For instance, a callback:
function getData(fileName) {
$.ajax({
async:false,
type: "GET",
url: "breastCancer.csv",
dataType: "text",
success: function (data) {
callback(processData(data));
},
});
}
...called like this:
getData(function(data) {
alert(data);
});
...or a promise ($.ajax returns one, of sorts):
function getData(fileName) {
return $.ajax({
async:false,
type: "GET",
url: "breastCancer.csv",
dataType: "text",
success: function (data) {
callback(processData(data));
},
}).then(data) {
return processData(data); // <== Becomes the resolution value of `getData`'s promise
});
}
and then
getData().then(function(data) {
alert(data);
});

data is undefined because the function getData doesn't return anything. You should have a look at promises.

Returning String Result from Ajax Method

I have a DoughnutChart chart and I would like to change the color of its parts regarding color hexa-codes saved in the database I used this Ajax method to get the color string by invoking an action method that returns JSON Result ,
getcolors: function getcolors(name) {
return $.ajax({
url: "/api/ideas/getcolors",
data: { name: name },
type: "GET",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (data, textStatus, jqXHR) {
// return data;
},
error: function (data) {
// return "Failed";
},
async: true
});
but instead of receiving the string I received Object {readyState: 1} in the console window
However, I can find the color value stored in ResponseText element.I need your help in how can I get the color value as string.
EDIT :
To make things more clear that's where I would like to invoke the ajax method to receive the color string then I will be able to push in the chart color array .
getColorArray: function getColorArray(categories) {
var colors = [];
for (var i = 0; i < categories.length; i++) {
console.log(this.getcolors("Risk"));
//colors.push(this.getcolors(categories[i]));
}
return colors;
}

Why your code is like this?
success: function (data, textStatus, jqXHR) {
// return data;
},
Did you use it?
success: function (data, textStatus, jqXHR) {
console.log(data);
}
Ok, i got it. When you use an ajax request your will work with asynchronous data, to do this you need return a promise in your method. Please, try to use the code below.
getcolors: function getcolors(name) {
return $.ajax({
url: "/api/ideas/getcolors",
data: { name: name },
type: "GET",
contentType: "application/json; charset=utf-8",
dataType: "json",
});
}
And for use your function use this code:
getcolors("name").done(function(result){
console.log(result);
});
Or you can use a callback
getcolors: function getcolors(name, success, error) {
return $.ajax({
url: "/api/ideas/getcolors",
data: { name: name },
type: "GET",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function(data){
success(data);
},
error: function(data){
error(data);
}
});
}
... And for use with callbacks:
getcolors("name", function(data){
//success function
console.log(data);
}, function(){
//Error function
console.log(data);
})
Try one of this options and tell the result.

The Solution
First of all I would like to thank Mateus Koppe for his efforts, through his solution I got the way to solve my problem ..
What I did simply is just I received the ResponseText from the incoming successful result in my Ajax method and then I passed it to a callback function that handles the result like the following :
getcolors: function getcolors(name, handleData) {
$.ajax({
url: "/api/ideas/getcolors",
data: { name: name },
type: "GET",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (data) {
handleData(data.responseText);
//return data.responseText;
},
error: function (data) {
handleData(data.responseText);
//return data.responseText;
},
async: false
});
then I worked with getColorArrayModified to loop through my categories list and populate its own color.
getColorArrayModified: function getColorArrayModified(categories) {
var colors = [];
for (var i = 0; i < categories.length; i++) {
this.getcolors(categories[i], function (output) {
colors.push(output);
});
}
return colors;
}
Thanks for all :).

ajax loading 2 XML documents in order without async:false

I am loading 2 XML documents that both run functions on success, although the function for the 2nd XML document is dependant on the 1st being complete.
If I have async:true:
1st XML
function XmlDataTypes() {
var result = null;
var scriptUrl = "http://domain.com/xml/test.XmlDataTypes?AccountId=" + AccountId;
$.ajax(
{
url: scriptUrl,
type: 'get',
dataType: 'xml',
async: true,
success: function (data) {
//create array to be used in second XML
for (var i = 0; i < xmlRows.length; i++) {
var dataType = xmlRows[i];
var dataTypeId = nodeValue(dataType.getElementsByTagName("DataTypeId")[0]);
var dataTypeName = nodeValue(dataType.getElementsByTagName("DataTypeName")[0]);
dataTypeArray.push({ dataTypeId: dataTypeId, dataTypeName: dataTypeName, position: i, markerArray: [] });
}
},
error: function onXmlError() {
alert("An Error has occurred.");
}
});
return result;
}
2nd XML
function XmlAmenityData() {
var result = null;
var scriptUrl = "http://domain.com/xml/test.XmlAmenityData?AccountId=" + AccountId;
$.ajax(
{
url: scriptUrl,
type: 'get',
dataType: 'xml',
async: true,
success: function (data) {
//store this info in markerArray in dataTypeArray
},
error: function onXmlError() {
alert("An Error has occurred.");
}
});
return result;
}
The XML data can loaded in a random order so the function for the second document will error if the 1st hasn't completed.
If I set:
async: false
It works correctly but I get a warning:
Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience.
Is there a way around this without using:
async: false

Since the 2nd xml is dependent on the 1st, you can define a callback on success.
Also since ajax is async, you must assign the result when the callback is called. You can define a variable ourside of your function (in this case an array) and put the data there.
var result = [];
function XmlDataTypes(url, accountId, callback) {
var scriptUrl = url + accountId;
$.ajax({
url: scriptUrl,
type: 'get',
dataType: 'xml',
async: true,
success: function (data) {
// do something
result.push(data);
if(typeof callback == 'function') {
callback();
}
},
error: function onXmlError() {
alert("An Error has occurred.");
}
});
}
function doSomething() {
// Do something to store this info in markerArray in dataTypeArray
// XmlAmenityData is in results var.
}
And you can use it like so
var _callback = XmlDataTypes("http://domain.com/xml/test.XmlAmenityData?AccountId=", "1234", doSomething);
XmlDataTypes("http://domain.com/xml/test.XmlDataTypes?AccountId=", "1234", _callback);
EDIT: Updated script based on given scenario.

You could try to return the $.ajax as a promise:
function XmlDataTypes() {
// note domain.com was changes to example.com - this should be changed back
var scriptUrl = "http://example.com/xml/test.XmlDataTypes?AccountId=" + AccountId;
return $.ajax(
{
url: scriptUrl,
type: 'get',
dataType: 'xml',
async: true,
success: function (data) {
//create array to be used in second XML
for (var i = 0; i < xmlRows.length; i++) {
var dataType = xmlRows[i];
var dataTypeId = nodeValue(dataType.getElementsByTagName("DataTypeId")[0]);
var dataTypeName = nodeValue(dataType.getElementsByTagName("DataTypeName")[0]);
dataTypeArray.push({ dataTypeId: dataTypeId, dataTypeName: dataTypeName, position: i, markerArray: [] });
}
},
error: function onXmlError() {
alert("An Error has occurred.");
}
});
}
Then calling them in sequence :
XmlDataTypes.done(XmlAmenityData);
Here is some more documentation :
http://www.htmlgoodies.com/beyond/javascript/making-promises-with-jquery-deferred.html

Periodicaly update ajax

I know the there is a lot of questions on this topic, but I really couldn't find anything what fits to my case. I defined this function in javascript:
self.ajax = function(uri, method, data) {
var request = {
url: uri,
type: method,
contentType: "application/json",
accepts: "application/json",
cache: false,
dataType: 'json',
data: JSON.stringify(data),
error: function(jqXHR) {
console.log("ajax error" + jqXHR.status);
}
};
return $.ajax(request);
}
And I call this function later like that:
self.ajax(self.tasksGetUri, 'POST', self.jsonRequest).done(function(data) {
for (var i = 0; i < data.tasks.length; i++) {
self.tasks.push({
user_id: ko.observable(data.tasks[i].user_id),
task_id: ko.observable(data.tasks[i].task_id),
done: ko.observable(data.tasks[i].done)
});
}
$(document).ready(function() {
for (var i = 0; i < self.tasks().length; i++) {
task = $("#" + self.tasks()[i].task_id());
if (task.length) {
task.slideUp(400);
task.parent().find(".unFinishedTask").hide();
task.parent().addClass("finished");
task.parent().find(".showTask").show();
}
}
});
});
Well, I want this calling of the function to be performed periodically together with return 'done()' function. I know the there is function setInterval(), but I don't know if it fits in my case. Can somebody recommend me some other solution ?
Thanks in advance for any help.

How to add each jquery array values inside the single quotes

I have a array in jquery.Now as per my need i have to add each array values into single quotes as ..
var toc='INCOMING','INETCALL','ISD','LOCAL','STD'
But at present i have values like this ..
var toc=INCOMING,INETCALL,ISD,LOCAL,STD
And here is my codes ..
$.ajax({
type: 'GET',
url: 'getdata',
async:false,
dataType: "text",
success: function(data) {
var values = [];
values = data;
values=values.replace('[','');
values=values.replace(']','');
var array = values.split(",");
for(var i=0,len=array.length;i<len;i++)
{
if($.isNumeric(array[i]))
{
callcost.push(array[i]);
}
else
{
toc.push(array[i]);
}
}
alert(toc);
alert(callcost);
}
});

not sure if i got your question right but i guess you are messing up with all this replace/split/... logic. If the data object is an array just try this
$.ajax({
type: 'GET',
url: 'getdata',
async:false,
dataType: "text",
success: function(data) {
var array = JSON.parse(data);
$.each(array, function(i, val){
if($.isNumeric(val)) {
callcost.push(val);
}else{
toc.push(val);
}
});
}
});