Javascript (jQuery) callback scope issue - javascript

The following is a little jQuery code that I wrote to check if a a username and email exists in database. If they do I return false to prevent submitting the form.
The way I planned it is something like this.
On submit after other stuff is valid. I use an ajax request to check if the username exists. If It does I then check the email in the same way.
And here is the problem. I cannot set the everythingIsOK inside the ajax callback. So if everything is ok I cannot return true.
Any ideas?
$(loginForm).submit(function(){
var = everythingIsOK = false;
if((loginForm).valid()){
$.get("/ajax/usernameAvailable", {username: $("#username").val()}, function(data){
if(data.available){
$.get("/ajax/emailAvailable", {email: $("#email").val()}, function(data){
if(data.available){
everythingIsOK = true;
return true;
}else{
$("#notAvailable").html("Email already exists.").show().fadeOut(8000);
return false;
}
}, "json");
}else{
$("#notAvailable").html("This is username already exist.").show().fadeOut(8000);
}
}, "json");
}
return everythingIsOK;
});

You can call the native form.submit() function (which won't trigger this handler again) if it is ok, and return false from the jQuery handler always, like this:
loginForm.submit(function(){
var form = this;
if(!loginForm.valid()) return false;
$.get("/ajax/usernameAvailable", {username: $("#username").val()}, function(data){
if(data.available){
$.get("/ajax/emailAvailable", {email: $("#email").val()}, function(data){
if(data.available) {
form.submit();
}else{
$("#notAvailable").html("Email already exists.").show().fadeOut(8000);
}
}, "json");
}else{
$("#notAvailable").html("This is username already exist.").show().fadeOut(8000);
}
}, "json");
return false;
});
When the check finishes (comes back from the server), you'll either get an error, or the form will submit and move on. Also I changed $(loginForm above to not be wrapped again, judging by if((loginForm).valid()){ (if that isn't erroring), it's already a jQuery object.

you have a syntax error on your second line:
var = everythingIsOK = false;
should be:
var everythingIsOK = false;
could that be the issue?

var = everythingIsOK = false;
should be
var everythingIsOK = false;
I guess. Maybe that's a first problem?

Instead of var = everythingIsOK = false; it should be var everythingIsOK = false;
Scope-wise, if that's not working, you can change it to be an attribute of an object var status = { everythingIsOK: false }; and change the value of that attribute.
However, you will need to always return false from your submit handler, because, as Nick points out, your get calls are asynchronous -- so they most-likely-will-not-have completed in time to prevent the form from submitting unless you do. (Take his advice and call submit manually from the interior get function's callback.)

Related

.preventDefault() is not working in conditionals

I have a bit of a problem. When a form is submitted, I wan't to check some things about it, and if something is wrong, I want to prevent it from submitting and then show an error on the client side. Everything seems to work fine except the form keeps submitting. It even shows the error on client side for a split second before it submits.
$('#register').on('submit', function (e) {
e.preventDefault();
var username = $("#register-username"),
name = $("#register-name"),
email = $("#register-email"),
password = $("#register-password"),
confirmPassword = $("#register-confirmPassword");
checkUsername(function (res) {
if (res) {
checkEmail(function (res) {
if (res) {
this.submit();
} else {
clearErrors();
email.toggleClass('input-error');
}
});
} else {
clearErrors();
username.toggleClass('input-error');
}
});
});
function checkEmail(callback) {
$.get("/checkEmail/" + $('#register-email').val(), function (data) {
if ( data == undefined ) {
callback(true);
} else {
callback(false);
}
});
}
function checkUsername (callback) {
$.get("/checkUsername/" + $('#register-username').val(), function (data) {
if ( data == undefined ) {
callback(true);
} else {
callback(false);
}
});
}
function clearErrors () {
var arr = [
$("#register-username"),
$("#register-name"),
$("#register-email"),
$("#register-password"),
$("#register-confirmPassword")
];
arr.forEach(function(el) {
el.removeClass('input-error');
});
}
Update:
Now I am just confusing myself. checkUsername() returns undefined from my server, I know for a fact, but somehow it is reaching the 'else' statement where checkUsername() is called. I've added the rest of my code. Should clear some confusion.
The call to preventDefault is made from the anonymous callback function you're passing to checkUsername. If the anonymous function is called asynchronously, then it's too late to cancel the event.
Assuming the problem is due to asynchronous code not shown, an effective way is to use preventDefault for the jQuery submit handler and use native submit when all validation passes
Something like:
$('#register').on('submit', function (e) {
e.preventDefault();// prevent jQuery submit
// after all validation passes
this.submit();// submit native method won't trigger jQuery handler again
})
You need to return false from validation to stop the current submitting event, and then manually send the post request on success from when the callbacks have successfully returned.
Since the callback is running after the validation has returned from the server then you can actually affect whether a request is made. Where as the other solutions involve trying to change how the original submit event occurs which is no longer in scope since you've already sent requests to the server at this point.
$('#register').on('submit', function (e) {
var username = $("#register-username"),
name = $("#register-name"),
email = $("#register-email"),
password = $("#register-password"),
confirmPassword = $("#register-confirmPassword");
checkUsername(function (res) {
if (res) {
checkEmail(function (res) {
if (res) {
$.post('{insert form action here}', $(this).serialize());
} else {
clearErrors();
email.toggleClass('input-error');
}
});
} else {
clearErrors();
username.toggleClass('input-error');
}
});
return false;
});
You'll have to replace the {insert form action here}, and $(this).action might work in it's place, but I'm not sure.
So I built off of charlietfl's solution and assigned the native form to a variable, and then submitted it within an anon function.
$('#register').on('submit', function (e) {
e.preventDefault()
var username = $("#register-username"),
name = $("#register-name"),
email = $("#register-email"),
password = $("#register-password"),
confirmPassword = $("#register-confirmPassword"),
form = document.getElementById('register');
$.get("/checkUsername/" + username.val(), function (data) {
if (data) {
clearErrors();
username.toggleClass('input-error');
} else {
$.get("/checkEmail/" + email.val(), function (data) {
if ( data ) {
clearErrors();
email.toggleClass('input-error');
} else {
form.submit();
}
});
}
});
});
This works.

Use JavaScript to submit Ajax.BeginForm()

I'm typing this question away from my computer so I don't have the exact code, but the question might be straightforward enough without it.
When I have a submit button directly within an Ajax form and I click the button directly to submit, everything works fine, and as expected. The Ajax.Form POSTs back to the controller which returns a partial view that is rendered inside the current View that I have.
But what I need is for a button to be clicked in the Ajax.Form, and for a JavaScript function to run. The JavaScript function will do some vaildation which decides whether to submit the Ajax.Form or not.
I have tried putting 2 buttons in the Ajax.Form, a hidden submit button and a regular button. I used the onclick event of the regular button to call my JavaScript function which then called the click method of the hidden submit button. (I have also tried just submitting the Ajax.Form directly with document.forms[formname].submit() )
This sort of works.. But not correctly for some reason. The Ajax.Form POSTs back to the controller but when a partial view is returned from the controller, the partial view is the only thing rendered, and it is rendered as basic html with no css/bootstrap.
What is the difference between actually clicking the submit button and doing so programmatically?
How can Achieve what I am trying to do?
Edit
#using (Ajax.BeginForm("GetInstructorInfo", "Incident", FormMethod.Post, new AjaxOptions { OnBegin = "lookupInstructor();", UpdateTargetId = "InstructorInfo" }, new { #class = "form-inline", role = "form", #id = "instructorInfoForm", #name = "instructorInfoForm" }))
{
//code in here
}
Edit 2 / 3:
<script>
function lookupInstructor()
{
if ($('input[name="Instructors['+userInputInstructor+'].Username'+'"]').length > 0) //Don't allow user to enter multiple instances of the same Instructor
{
document.getElementById("InstructorUsername").value = ''; //clear textbox value
return false;
}
var userInputInstructor = document.getElementById("InstructorUsername").value;
$.ajax({
url: '#Url.Content("~/Incident/LookUpUsername")',
data: { userInput: userInputInstructor },
success: function (result) {
if (result.indexOf("not found") != -1){ //if not found
$("#InstructorNotFoundDisplay").show();
document.getElementById("InstructorUsername").value = ''; //clear textbox value
$('#InstructorInfo').empty();
return false;
}
else {
$("#InstructorNotFoundDisplay").hide();
return true;
}
}
});
}
</script>
You can use the OnBegin() ajax option to call a function that runs before the form is submitted (and return false if you want to cancel the submit). For example
function Validate() {
var isValid = // some logic
if (isValid) {
return true;
} else {
return false;
}
}
and then in the Ajax.BeginForm() options
OnBegin = "return Validate();"
Edit
Based on the edits to the question and the comments, you wanting to call an ajax function in the OnBegin() option which wont work because ajax is asynchronous. Instead, use jQuery.ajax() to submit you form rather than the Ajax.BeginForm() method (and save yourself the extra overhead of including jquery.unobtrusive-ajax.js).
Change Ajax.BeginForm() to Html.BeginForm() and inside the form tags replace the submit button with <button type="button" id="save">Save</button>and handle its .click() event
var form = $('#instructorInfoForm');
var url = '#Url.Action("GetInstructorInfo", "Incident")';
var target = $('#InstructorInfo');
$('#save').click(function() {
if ($('input[name="Instructors['+userInputInstructor+'].Username'+'"]').length > 0) {
....
return; // exit the function
}
$.ajax({
....
success: function (result) {
if (result.indexOf("not found") != -1) {
....
}
else {
$("#InstructorNotFoundDisplay").hide();
// submit the form and update the DOM
$.post(url, form.serialize(), function(data) {
target.html(data);
});
}
}
});
});

Delayed submit results in multiple continuous submits

I have the following jQuery code, the point of this code is to create a short time delay, so the AJAX request gets time to execute properly:
$('#form_id').submit(function(e) {
e.preventDefault();
$submit_url = $(this).data('submitUrl');
$submit_url = $submit_url.replace('http://','').replace(window.location.host,'');
if ($(this).data('toBeAjaxSubmitted') == true) {
$.ajax($submit_url, {
type : $(this).attr('method'),
data : $(this).serialize(),
complete : function(data) {
$(this).data('toBeAjaxSubmitted', false);
$('#form_id').submit();
}
});
}
});
What happens is, the form starts off with a submit url that I need to submit to in order for the component to save an entry to the database. But I also need user input to submit directly to a payment gateway URL where the user then makes a payment.
The code above creates the AJAX request, but does not return to normal postback behaviour (via $('#form_id').submit()).
It keeps submitting the form over and over, but never posts to the gateway URL or redirects out.
What am I doing wrong?
The following worked for me after some more debugging:
$('#chronoform_Online_Submission_Step8_Payment').submit(function(e) {
var form = this;
e.preventDefault();
$submit_url = $(this).data('submitUrl');
$submit_url = $submit_url.replace('http://','').replace(window.location.host,'');
if ($(this).data('toBeAjaxSubmitted') == true) {
$.ajax($submit_url, {
type : $(this).attr('method'),
data : $(this).serialize(),
complete : function(data, status) {
}
}).done(function() {
form.submit();
});
}
});
What really put me on the wrong path was that in Chrome's Developer Tools I had the following option enabled 'Disable cache (while DevTools is open)' and this was causing some headaches with inconsistent behaviour between Safari, Firefox (which worked) and Chrome which did not.
What about some fiddling with this approach?
$('#form_id').submit(function(e) {
// closures
var $form = $(this);
var fAjaxComplete = function(data) {
// don't send the ajax again
$form.data('toBeAjaxSubmitted', 'false');
// maybe do some form manipulation with data...
// re-trigger submit
$form.trigger('submit');
};
var oAjaxObject = {
type : $form.attr('method'),
data : $form.serialize(),
complete : fAjaxComplete
};
var sSubmitUrl = $form.data('submitUrl');
// scrub url
sSubmitUrl = sSubmitUrl.replace('http://','').replace(window.location.host,'');
// if ajax needed
if ($form.data('toBeAjaxSubmitted') != 'false') {
// go get ajax
$.ajax(sSubmitUrl, oAjaxObject);
// don't submit, prevent native submit behavior, we are using ajax first!
e.preventDefault();
return false;
}
// if you got here, go ahead and submit
return true;
});

async html5 validation

For some reason html5 validation message is not shown when I'm using an async request.
Here you can see an example.
http://jsfiddle.net/E4mPG/10/
setTimeout(function() {
...
//this is not working
target.setCustomValidity('failed!');
...
}, 1000);
When checkbox is not checked, everything works as expected,
but when it is checked, the message is not visible.
Can someone explain what should be done?
I figured it out, turns out that the HTML5 validation messages will only popup when a form submit is in progress.
Here is the process behind my solution (when timeout is checked):
Submits the form
Sets the forceValidation flag
Sets the timeout function
When the timeout function is called, resubmit the form
If the forceValidation flag is set, show the validation message
Basically perform two submits, the first one triggered by the button, and the second triggered when the timeout function is called.
jsFiddle
var lbl = $("#lbl");
var target = $("#id")[0];
var forceValidation = false;
$("form").submit(function(){
return false;
});
$("button").click(function (){
var useTimeout = $("#chx").is(":checked");
lbl.text("processing...");
lbl.removeClass("failed");
target.setCustomValidity('');
showValidity();
if (forceValidation) {
forceValidation = false;
lbl.text("invalid!");
lbl.addClass("failed");
target.setCustomValidity('failed!');
showValidity();
} else if (useTimeout) {
setTimeout(function () {
forceValidation = true;
$("button").click();
}, 1000);
} else {
lbl.text("invalid without timeout!");
lbl.addClass("failed");
target.setCustomValidity('failed!');
showValidity();
}
});
function showValidity() {
$("#lbl2").text(target.checkValidity());
};
I am running on Chrome version 25.0.1364.172 m.

Getting a form to submit from JavaScript?

I have a form in a JSP as follows:
<form action = "<c:url value = '/displayVisualisation' />"
title = "${item.visDescription}"
method = "post" onClick = "return confirmRequest('Do you want to change to
another visualisation type?');">
<input class = "text" type = "text" value = "${item.visTypeName}">
</form>
Which calls a Javascript method as follows:
function confirmRequest(questionText) {
var confirmRequest = confirm(questionText);
if (confirmRequest) {
return true;
}
else {
return false;
}
}
To ask the user for a reply to the question asked. However, the confirm prompt appears but does not perform the displayVisualisation action!
Can anyone suggest why or help me implement this correctly?
In other examples, where the action is triggered by clicking a graphic, all is well.
Since you are using onclick, return true; in your confirmRequest function is simply allowing the rest of the clickHandler chain to be executed. I think you also need to explicitly submit the form at this time, in the true case.
Here is one way to do that, using only javascript:
function confirmRequest(questionText) {
var confirmRequest = confirm(questionText);
if (confirmRequest) {
document.forms[0].submit();
return true;
}
else {
return false;
}
}

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