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I want to return function result after calculating in a for loop

i want to check whether is a valid item or not before saving the values. then i create java-script function to check validation and return result. but the problem is this function returns before validate items, the always true the condition above if condition. my code is below. could anyone help me please?
this is series of ajax call and i'm not aware of how to use callback for this..
if(IsValidItems() != ''){
//Do something
}
function IsValidItems() {
var IsvalidStatus = '';
var lineqty = 0;
var LineNumber = -1;
var allRowData = jQuery("#tblJQGrid").jqGrid("getRowData");
for (var i = 0; i < allRowData.length - 1; i++) {
if (allRowData[i].BulkItem != "False") {
if (allRowData[i].quantity != '') {
lineqty = parseInt(allRowData[i].quantity);
LineNumber = i + 1;
var postURL = "/BookingDetail/GetItemAvailablity?ItemCode=" + allRowData[i].itemCode + "&StartDate=" + allRowData[i].StartDate + "&EndDate=" + allRowData[i].EndDate + "&srno=" + allRowData[i].srno + "&locationID=" + allRowData[i].Location;
$.ajax({
url: postURL,
dataType: "json",
contentType: "application/json; charset=utf-8",
data: "",
type: "POST",
async: true,
dataFilter: function (data) {
return data;
},
success: function (result) {
if (lineqty > parseInt(result)) {
IsvalidStatus = IsvalidStatus + "," + LineNumber;
}
},
error: function (XMLHttpRequest, textStatus, errorThrown) { }
});
}
}
}
return IsvalidStatus;
}

rerturning response of an ajax post

i am trying to check if an email exists in the db but the function doesn't return a value.
This is the code:
function checkemail(email)
{
var returnVal = "";
if (email.indexOf("#") != -1 && email.indexOf(".") != -1)
{
$.post( "registreren.php?email=" + email, function( response ) {
if(response == 1) { returnVal = 1; }
if(response == 2) { returnVal = 2; }
});
}
else
{
returnVal = 3;
}//email
return returnVal;
}
EDIT: email is send as a string

I short, You can not return values from ajax calls as it is asynchronous by nature, the statement return value executes before
To address such cases, use callback, a function accepted as argument and which is executed when response is been received (when asynchronous action is completed).
Try this:
function checkemail(email, callback) {
var returnVal = "";
if (email.indexOf("#") != -1 && email.indexOf(".") != -1) {
$.post("registreren.php?email=" + email, function(response) {
callback(response);
});
} else {
callback(3);
}
}
checkemail('abc#xyz.com', function(val) {
alert(val);
});
checkemail('INVALID_EMAIL', function(val) {
alert(val);
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

Can you use something simple like below
$.ajax({
url: 'registreren.php',
type: 'post',
dataType: "json",
data: {'email': email},
success: function (response) {
if (response == 1)
{
returnVal = 1;
}
else
{
returnVal = 3;
}
}
});
instead of
$.post( "registreren.php?email=" + email, function( response ) {
if(response == 1) { returnVal = 1; }
if(response == 2) { returnVal = 2; }
});

Validation error not displaying with AJAX

I have been struggle with this now for two days and I do not know where the problem is.
When I leave the textbox the Ajax call is correct and the result are returned as a true or false and the success: function is executing.
The problem is that the image and error text is not displaying next to the textbox. If I type in more than 50 characters in the textbox the "Must be under 50 characters" message is showing but it I type in a user name that already exist the message is not showing.
What am I missing? Any suggestions?
I use a DevExpress Text Box
Html.DevExpress().Label(
edtSettings =>
{
edtSettings.ControlStyle.CssClass = "label";
edtSettings.Text = "User Name:";
edtSettings.AssociatedControlName = "UserName";
}
)
.Render();
Html.DevExpress().TextBox(
edtSettings =>
{
edtSettings.Name = "UserName";
edtSettings.ControlStyle.CssClass = "editor";
edtSettings.ShowModelErrors = true;
edtSettings.Width = 100;
edtSettings.Properties.ValidationSettings.Assign(IserValidationHelper.UserNameValidationSettings);
edtSettings.Properties.ClientSideEvents.Validation = "OnNameValidation";
edtSettings.ControlStyle.BackColor = System.Drawing.Color.LightYellow;
}
)
.Bind(DataBinder.Eval(IserUser, "UserName"))
.Render();
I have the following JavaScript.
<script type="text/javascript">
function OnNameValidation(s, e) {
if (e.value == null)
e.isValid = false;
$.ajax({
type: 'POST',
url: '/Admin/CheckUsername',
dataType: 'json',
data: { userName: e.value },
error: function () { alert("error"); },
success: function (Data) {
if (Data.result == true) {
e.isValid = false;
e.errorText = "User Exits";
};
}
});
var name = e.value;
if (name == "")
e.isValid = false;
if (name.length > 50) {
e.isValid = false;
e.errorText = "Must be under 50 characters";
}
}
I have the following method in my controller.
[HttpPost]
public ActionResult CheckUsername(string userName)
{
bool status = WebSecurity.UserExists(userName);
return Json(new { result = status });
}

The problem was with my $.ajax call. I had to include the setting async (async:false,) as the default async is true. It is working now correctly.
function OnNameValidation(s, e) {
if (e.value == null)
e.isValid = false;
$.ajax({
type: 'POST',
url: '/ISERAdmin/CheckUsername',
dataType: 'json',
async:false,
data: { userName: e.value },
error: function () { alert("error"); },
success: function (Data) {
if (Data.result == true) {
e.isValid = false;
e.errorText = "User Exits";
};
}
});
var name = e.value;
if (name == "")
e.isValid = false;
if (name.length > 56) {
e.isValid = false;
e.errorText = "Must be under 56 characters";
}
}

Why don't work my function xmlParser(). Help me please

Hello everybody. I have a problem with my code. I use the jquery framework. When I want to call $.ajax(requestOptions), function xmlParser(xml) don't working.
I try to find a resolve this problem, but I can't nothing find.
$(document).ready(function () {
var requestOptions = {
type: "GET", //The method
url: "Course_Valute_02-07-2014.xml", //It is reference on xml file
dataType: "xml", //The type of data
crossDomain: true, //Allow to do the cross-domain request
success: xmlParser //Calling function
};
function xmlParser(xml) {
$("#load").fadeOut();
$(xml).find("Valute").each(function() {
$("#outputListValutes").append(
"<option value=" + $(this).find("CharCode").text() + ">" + $(this).find("CharCode").text() + "</option>");
});
};
$.ajax(requestOptions);
$("#clear").click(function() {
var sumValue = document.getElementById("sum").value = "";
var resValue = document.getElementById("result").value = "";
});
$("#convert").click(function(xml) {
//var selectCurrency = $("#inputListCurrency").val();
//findData(xml);
}(requestOptions));
function findData(xml) {
var decimalOnly = /^\s*-?[1-9]\d*(\.\d{1,2})?\s*$/;
try{
var shortName = $("#outputListCurrency").val();
var value = $("#sum").val();
if(value == "") throw new Error("Empty value");
else if(!decimalOnly.test(value)) throw new Error("value must be of decimal digits");
else if(value < 0) throw new Error("Value isn't to be below zero");
else if(isNaN(parseFloat(value))) throw new Error("Value isn't to be as symbols");
$(xml).find("Valute").each(function() {
if(shortName == $(this).find("CharCode").text()) {
var nominal = $(this).find("Nominal").text();
var course = $(this).find("Value").text();
var result = parseFloat(value) * parseFloat(nominal) / parseFloat(course);
document.getElementById("result").value = Number(result).toFixed(2);
}
});
}
catch(e) {
alert(e);
}
}
});

change the success parameter of the request to use the xmlParser function (forgot () ):
var requestOptions = {
type: "GET", //The method
url: "Course_Valute_02-07-2014.xml", //It is reference on xml file
dataType: "xml", //The type of data
crossDomain: true, //Allow to do the cross-domain request
success: xmlParser(data) //Calling function
};

I found the solution this promlem. I am happy.
var courseFilePath = "xml/Course_Currency_02-07-2014.xml";
var listCurrency = [];
function insertOptions(){
for (var i = 0; i < listCurrency.length; ++i){
$("#outputListCurrency").append(
"<option value=" + listCurrency[i] + ">" + listCurrency[i] + "</option>");
}
}
function xmlParser(xml){
$("#load").fadeOut();
$(xml).find("Valute").each(function(){
var value = $(this).find("CharCode").text();
listCurrency.push(value);
});
listCurrency.sort();
};
function findData(xml){
var decimalOnly = /^\s*-?[0-9]\d*(\.\d{1,2})?\s*$/;
try {
var shortName = $("#outputListCurrency").val();
var value = $("#sum").val();
if (value == "") throw new Error("Empty value");
else if (!decimalOnly.test(value)) throw new Error("value must be of decimal digits");
else if (value < 0) throw new Error("Value isn't to be below zero");
else if (isNaN(parseFloat(value))) throw new Error("Value isn't to be as symbols");
$(xml).find("Valute").each(function(){
if (shortName == $(this).find("CharCode").text()){
var nominal = $(this).find("Nominal").text();
var course = $(this).find("Value").text();
var result = parseFloat(value) * parseFloat(nominal) / parseFloat(course);
document.getElementById("result").value = Number(result).toFixed(2);
}
});
}
catch (e){
alert(e);
}
}
$(document).ready(function(){
$.ajax({
type: "GET", //The method of sending for data
url: courseFilePath, //It is reference on xml file
dataType: "xml", //The type of data
success: function(xml){
xmlParser(xml);
insertOptions();
}
});
//insertOptions();
$("#clear").click(function() {
document.getElementById("sum").value = "";
document.getElementById("result").value = "";
});
$("#convert").click(function() {
var selectCurrency = $("#inputListCurrency").val();
$.get(courseFilePath, findData, "xml");
});
});

Javascript does user exists, returning value from ajax to late?

I have a script that tells a visitor if the username is already exist or not before he can proceed,
Below you see a part of my code;
EDIT: Ok I have read what you guys said, and modified it, but I still dont get it to work :S, my teacher doesn't know it either...
<script type="text/javascript">
jQuery(document).ready(function(){
// Smart Wizard
jQuery('#wizard').smartWizard({onFinish: onFinishCallback, onLeaveStep: onNextStep});
function onNextStep(){
validateSteps(function (next) { return next; });
}
function onFinishCallback(){
alert('Finish Clicked');
}
function UsernameExist(fullname, callback)
{
    var data = 'user='+ fullname;
    if(fullname) {
        $.ajax({
            type: "POST",
            url: "user_check.php",
            data: data,
async: false,
            beforeSend: function(html) {
                $("#msg_lastname").html('');
            },
            success: function(html){
                $("#msg_lastname").show();
                 $("#msg_lastname").append(html);
if(html.search("red") != -1)
{
callback(false);
}
else
{
callback(true);
}
            }
        });
}
}
function validateSteps(callback){
var isStepValid = true;
// validate step 1
var firstname = $('#firstname').val();
if(!firstname || (firstname.length < 3 || firstname.length > 10))
{
$('#msg_firstname').html('<br/><font color="red">Enter a first name, between 3 and 10 letters.</font>').show();
isStepValid = false;
}
else
{
$('#msg_firstname').html('').hide();
}
var lastname = $('#lastname').val();
if(!lastname || (lastname.length < 3 || lastname.length > 14))
{
$('#msg_lastname').html('<br/><font color="red">Enter a last name, between 3 and 14 letters.</font>').show();
isStepValid = false;
}
else
{
$('#msg_lastname').html('').hide();
}
var gender = $('#gender').val();
if(!gender || Number(gender) == -1)
{
$('#msg_gender').html('<br/><font color="red">Choose your gender!</font>').show();
isStepValid = false;
}
else
{
$('#msg_gender').html('').hide();
}
var age = $('#age').val();
if(!age || Number(age) > 90 || Number(age) < 21)
{
$('#msg_age').html('<br/><font color="red">Enter a age between 21 and 90.</font>').show();
isStepValid = false;
}
else
{
$('#msg_age').html('').hide();
}
var pin = $('#pin').val();
if(!pin || pin.length > 10 || pin.length < 4)
{
$('#msg_pin').html('<br/><font color="red">Enter a PIN between 4 and 10 numbers.</font>').show();
isStepValid = false;
}
else
{
$('#msg_pin').html('').hide();
}
if (isStepValid) {
UsernameExist(firstname + ' ' + lastname, function (exists) {
callback( exists );
});
} else {
callback( false );
}
}
jQuery('select, input:checkbox').uniform();
});
</script>
Now the problem is that when I run this script, it returns undefined, I guess because the UsernameExist is not done fast enough, and it seems the return UsernameExist is not waiting for it for some reason...

You are returning UsernameExists before it has been run.
Instead, call UsernameExists like this:
if (isStepValid) {
UsernameExist(firstname + ' ' + lastname, function (exists) {
return exists;
});
} else {
return false;
}
This works because UsernameExists expects a callback function and on success passes either true or false to callback().

you need just to set async option as false
function UsernameExist(fullname, callback) {
var data = 'user=' + fullname;
if (fullname) {
$.ajax({
type: "POST",
url: "user_check.php",
data: data,
async: false,
beforeSend: function (html) {
$("#msg_lastname").html('');
},
success: function (html) {
//your code after success
}
});
}
}
from jQuery documentation jQuery.ajax
If you need synchronous requests, set this option to false
so you need to execute your ajax call and wait until it's completely finish to execute what you want based on the result

Maybe you should call UsernameExist(fullname, callback) after jQuery load complete.
try this :
getScript('http://code.jquery.com/jquery-1.9.1.min.js', function () {UsernameExist(fullname, callback)});
function getScript(url, callback) {
var script;
script = document.createElement("script");
script.setAttribute('language', 'javascript');
script.setAttribute('type', 'text/javascript');
script.setAttribute('src', url);
var done = false;
vObj = script.onload;
script.onload = script.onreadystatechange = function () {
if (!done && (!this.readyState ||
this.readyState == "loaded" || this.readyState == "complete")) {
done = true;
if (typeof callback === 'function')
callback(this.ownerDocument.attributes);
}
};
var head = document.getElementsByTagName('head')[0];
head.appendChild(script);}

Try something like this :
// Smart Wizard
$('#wizard').smartWizard({onFinish: onFinishCallback, onLeaveStep: onNextStep});
function onNextStep() {
var isValid = validateSteps();
alert(isValid);
}
function onFinishCallback(){
alert('Finish Clicked');
}
function UsernameExist(fullname)
{
var data = 'user='+ fullname;
var userAlreadyExists = null;
if(fullname) {
$.ajax({
type: "POST",
url: "user_check.php",
data: data,
async: false,
beforeSend: function(html) {
$("#msg_lastname").html('');
},
success: function(html){
$("#msg_lastname").show();
$("#msg_lastname").append(html);
if(html.search("red") != -1)
{
userAlreadyExists = false;
}
else
{
userAlreadyExists = true;
}
}
});
}
return userAlreadyExists;
}
function validateSteps(){
...
if (isStepValid) {
return UsernameExist(firstname + ' ' + lastname);
} else {
return false;
}
}