I've spent some time looking around and trying multiple solutions without luck, while attempting to streamline a form to create a pseudo bulk process.
Essentially I simply need to prevent default on a submit button, but to trigger it if several subconditions are met, at least one of which uses an ajax call.
I've tried variations of e.preventDefault, $('#form').submit(false); and I can either get the validation to occur, or the form to submit, but never both in the right places. (for example it will submit without checking for duplicate entries)
Here's a summed up version of what I've been attempting.
This is the main variable which holds the first part of the check:
var verifyValue = function() {
// this stops the form, and then things validate fine.
$('#add-item-form').submit(false);
//but then I need to get it started again to submit valid entries
if($('#value_of_json_array').val().length != 0){
$('#value_of_json_array').prop("readonly", true);
jQuery.getJSON('{{ path('query_to_get_array') }}?' +
$.param({barcode: $('#value_of_json_array').val()}))
.done(checkedValue);
}
};
This is where it is called:
$("#verify-value").click(verifyValue);
Below is a shorthand of the conditional being run:
var checkedValue = function(items) {
if(items.length == 0){
// success conditions
}
else {
//this was just one attempt
$('#form').submit(false);
if( /* sub condition of data passed from JSON array */){
//condition creates new form which upon action sends AJAX call
}
else
{
//second error condition
}
}
};
What I'm trying to do is to have if any of the subconditions occur, to have it stop the submit button (e.g. preventDefault behavior) and if it does not have any of these, to allow the submission of the form
It feels like it should be simple, however no matter where I do this, including using $(this).unbind('submit').submit() It doesn't work right.
Either the validation occurs correctly and nothing submits, or everything submits even if it's not supposed to.
I feel like modifying var verifyValue will work but I'm not sure how to get the conditional statements bound into an event.
Edit:
Okay, so I was guilty of seriously overthinking this issue, and came up with a solution which I will put below (in case anyone is interested)
Since your validation includes an async step, it'd be easier to just stop the form submission right away.
Then call your validation function, which will set the validation state of the form in a "global" state (maybe just a closure of the event handler). If the validation is fine, submit the form, else just show the validation error.
// You'll need to reset this if an input changes
var isFormValid = false;
$("#form").on('submit', function(e) {
if (isFormValid) {
return true;
}
e.preventDefault();
validateForm(function(valid) {
if (valid) {
isFormValid = true;
$('#form').submit();
}
});
});
function validateForm(cb) {
var form = $('#form');
// do some synchronous validations on the form inputs.
// then do the async validation
if($('#value_of_json_array').val().length != 0){
$('#value_of_json_array').prop("readonly", true);
jQuery
.getJSON(
'{{ path('query_to_get_array') }}?' +
$.param({barcode: $('#value_of_json_array').val()})
)
.done(function(result) {
if (checkedValue(result)) {
cb(true);
} else {
cb(false);
}
});
} else {
cb(false);
}
}
How about this approach, here's a simple skeleton:
$('#form').submit(function(e){
var formError = false;
// set formError to true if any of the checks are not met.
if(some condition) {
// do a conditional check
formError = true;
} else if(another condition) {
// do another conditional check
formError = true;
}
if(formError) { // stop form submission of any of the conditions are not met.
return false; // same as e.preventDefault and e.stopPropagate()
}
});
It turned out I was seriously overthinking this issue. It was a lot easier to handle by binding everything into a button that was not a submit, and if it passed the validation simply use a submit condition. This way I didn't need to worry about preventing default behavior and turning it back on again (which was where I was getting stuck). Since regular buttons have no default behavior, there was no need to be concerned about it submitting incorrectly.
The original function just needed to be simplified to:
var verifyValue = function() {
if($('#value_of_json_array').val().length != 0){
$('#value_of_json_array').prop("readonly", true);
$('#barcode-buttons').hide();
jQuery.getJSON('{{ path('query_to_get_array') }}?' +
$.param({barcode: $('#value_of_json_array').val()}))
.done(checkedValue);
}
};
$("#verify-value").click(verifyValue);
and then the check only needed to do this
var checkedValue = function(items) {
if(items.length == 0){
$('#form').submit()
}
else {
//error conditions
}
};
Can someone explain me why this snippet can't work ?
I can't use specific features like window.location, submit(), (instead of trigger()), because this function is bound to elements that are very differents.
$('a, button').bind('click', function(oEvent, oData) {
var oButton = $(this);
var bSkip = (oData && oData.skip);
if(true === bSkip) {
return true;
} else {
oEvent.preventDefault();
//oEvent.stopPropagation();
if(confirm('This is a confirm box')) {
$(oButton).trigger('click', { skip: true });
}
}
});
Thanks in advance ! ;)
In your case even though the click event gets fired the default behavior of the links may not be triggered because of the constraints imposed by the browser
If I understand what you are trying to do correctly(if the action s not confirmed then cancel the default behavior), then you can achieve it by the below... there is no need to fire the event again
$('a, button').bind('click', function (oEvent, oData) {
if (confirm('This is a confirm box')) {
return true;
} else {
oEvent.preventDefault();
}
});
Demo: Fiddle
I have a little code like this:
$("input#checkbox").change(changeCheckbox);
function changeCheckbox() {
var inputCheck = $("input#checkbox"),
button = $("input#button");
if (inputCheck.is(":checked")) {
button.hide();
} else {
button.show();
}
}
This work perfect in all modern Browser and IE 8
But when I use this one with event.preventDefault();:
$("input#checkbox").change(changeCheckbox);
function changeCheckbox(event) {
event.preventDefault(); // <-- Here
var inputCheck = $("input#checkbox"),
button = $("input#button");
if (inputCheck.is(":checked")) {
button.hide();
} else {
button.show();
}
}
or I set return false;
$("input#checkbox").change(changeCheckbox);
function changeCheckbox() {
var inputCheck = $("input#checkbox"),
button = $("input#button");
if (inputCheck.is(":checked")) {
button.hide();
} else {
button.show();
}
return false; // <-- Here
}
then the function only works once and I can do nothing more with this in (only) Internet Explorer 8
Can someone explain to me why this happens?
And i have a lot of other functions and use similar codes with event.preventDefault(); and return false; at the end and there are OK...
I use this jQuery Version: jquery_1.10.1.min.js
Thanks in advance!
Can someone explain to me why this happens?
It's a bug in Internet Explorer (what else). The change event is supposed to be not cancelable, in contrast to click events (see Is event.preventDefault cancelling change events?, jQuery/Javascript: Click event on a checkbox and the 'checked' attribute and Why does preventDefault() on a parent element's click 'disable' a checkbox?). IE8 however does prevent the checkbox from being (un)checked when the change event is canceled. Try it here.
How to work around that? Just remove e.preventDefault() (or return false) from your code. I don't see any reason to use it anyway.
What you want to achieve is to show/hide #button based on the value of #checkbox. You can do it this way. Very less lines of code as compared to your code
$('#checkbox').on('change', function() {
$('#button').toggle(this.checked);
});
FIDDLE
You can add this code for IE8:
if (event.preventDefault) event.preventDefault();
else event.returnValue = false;
Since you are using jQuery you can use the built-in cross-browser event fix:
event = $.event.fix(event);
See: http://www.jquerysdk.com/api/jQuery.event.fix
i have a page on which i want to confirm if the user wants to leave.
i have to confirm only when a certain condition is met so i wrote code like this
var back=false;
back=//check if user pressed back button
window.onbeforeunload = function (e) {
alert(back); //this alerts true
if(back==true)
return false;
//e.preventDefault; --this does not work too
};
but this does not work. i mean when i click on back button this onbeforeunload still fires and i still get the confirmation message even when i m returning false.Whats can be wrong?
Thanks
Return a string if you want to offer an option to the user to abort the unload. Return nothing in other cases.
var back = false;
back = true; //Somewhere, the condition is set to true
window.onbeforeunload = function (e) {
if(back == true)
return "Are you sure to exit?";
}
$(window).bind('beforeunload',function() {
return "'Are you sure you want to leave the page. All data will be lost!";
});
$('#a_exit').live('click',function() {
$(window).unbind('beforeunload');
});
Try this. Above code is working in most of conditions.
For the sake of completeness here a more modern, recommended approach:
let warn = false;
window.addEventListener('beforeunload', e => {
if (!warn) return;
// Cancel the event
e.preventDefault();
// Chrome requires returnValue to be set
e.returnValue = '';
});
warn = true; // during runtime you change warn to true
Typically, it is better to use window.addEventListener() and the
beforeunload event, instead of onbeforeunload.
Source
The reason why your originally posted code didn't work is that false is a non-null value. If you would have returned null or undefined in the situation where you don't want to spawn a pop-up warning your code would have worked as expected.
The currently accepted answer works because JavaScript implicitly returns undefined at the end of the function.
Condition for back-end
var confirmExist = function (e) {
return true;
}
window.onbeforeunload = confirmExist;
http get, post request
.then(function(r)) {
window.onbeforeunload = null;
}
You could also consider not setting the window.beforeunload event untill your list of conditions are met.
var confirmUserToLeave = function () {
if (/* conditions are met */) {
window.unbeforeunload = function (e) {
/* whatever you want to do here */
};
} else {
window.unbeforeunload = undefined;
}
};
Then just call that method on certain events that might change the outcome of your 'conditions are met'.
I have a requirement to implement an "Unsaved Changes" prompt in an ASP .Net application. If a user modifies controls on a web form, and attempts to navigate away before saving, a prompt should appear warning them that they have unsaved changes, and give them the option to cancel and stay on the current page. The prompt should not display if the user hasn't touched any of the controls.
Ideally I'd like to implement this in JavaScript, but before I go down the path of rolling my own code, are there any existing frameworks or recommended design patterns for achieving this? Ideally I'd like something that can easily be reused across multiple pages with minimal changes.
Using jQuery:
var _isDirty = false;
$("input[type='text']").change(function(){
_isDirty = true;
});
// replicate for other input types and selects
Combine with onunload/onbeforeunload methods as required.
From the comments, the following references all input fields, without duplicating code:
$(':input').change(function () {
Using $(":input") refers to all input, textarea, select, and button elements.
One piece of the puzzle:
/**
* Determines if a form is dirty by comparing the current value of each element
* with its default value.
*
* #param {Form} form the form to be checked.
* #return {Boolean} <code>true</code> if the form is dirty, <code>false</code>
* otherwise.
*/
function formIsDirty(form) {
for (var i = 0; i < form.elements.length; i++) {
var element = form.elements[i];
var type = element.type;
if (type == "checkbox" || type == "radio") {
if (element.checked != element.defaultChecked) {
return true;
}
}
else if (type == "hidden" || type == "password" ||
type == "text" || type == "textarea") {
if (element.value != element.defaultValue) {
return true;
}
}
else if (type == "select-one" || type == "select-multiple") {
for (var j = 0; j < element.options.length; j++) {
if (element.options[j].selected !=
element.options[j].defaultSelected) {
return true;
}
}
}
}
return false;
}
And another:
window.onbeforeunload = function(e) {
e = e || window.event;
if (formIsDirty(document.forms["someForm"])) {
// For IE and Firefox
if (e) {
e.returnValue = "You have unsaved changes.";
}
// For Safari
return "You have unsaved changes.";
}
};
Wrap it all up, and what do you get?
var confirmExitIfModified = (function() {
function formIsDirty(form) {
// ...as above
}
return function(form, message) {
window.onbeforeunload = function(e) {
e = e || window.event;
if (formIsDirty(document.forms[form])) {
// For IE and Firefox
if (e) {
e.returnValue = message;
}
// For Safari
return message;
}
};
};
})();
confirmExitIfModified("someForm", "You have unsaved changes.");
You'll probably also want to change the registration of the beforeunload event handler to use LIBRARY_OF_CHOICE's event registration.
In the .aspx page, you need a Javascript function to tell whether or not the form info is "dirty"
<script language="javascript">
var isDirty = false;
function setDirty() {
isDirty = true;
}
function checkSave() {
var sSave;
if (isDirty == true) {
sSave = window.confirm("You have some changes that have not been saved. Click OK to save now or CANCEL to continue without saving.");
if (sSave == true) {
document.getElementById('__EVENTTARGET').value = 'btnSubmit';
document.getElementById('__EVENTARGUMENT').value = 'Click';
window.document.formName.submit();
} else {
return true;
}
}
}
</script>
<body class="StandardBody" onunload="checkSave()">
and in the codebehind, add the triggers to the input fields as well as resets on the submission/cancel buttons....
btnSubmit.Attributes.Add("onclick", "isDirty = 0;");
btnCancel.Attributes.Add("onclick", "isDirty = 0;");
txtName.Attributes.Add("onchange", "setDirty();");
txtAddress.Attributes.Add("onchange", "setDirty();");
//etc..
The following uses the browser's onbeforeunload function and jquery to capture any onchange event. IT also looks for any submit or reset buttons to reset the flag indicating changes have occurred.
dataChanged = 0; // global variable flags unsaved changes
function bindForChange(){
$('input,checkbox,textarea,radio,select').bind('change',function(event) { dataChanged = 1})
$(':reset,:submit').bind('click',function(event) { dataChanged = 0 })
}
function askConfirm(){
if (dataChanged){
return "You have some unsaved changes. Press OK to continue without saving."
}
}
window.onbeforeunload = askConfirm;
window.onload = bindForChange;
Thanks for the replies everyone. I ended up implementing a solution using JQuery and the Protect-Data plug-in. This allows me to automatically apply monitoring to all controls on a page.
There are a few caveats however, especially when dealing with an ASP .Net application:
When a user chooses the cancel option, the doPostBack function will throw a JavaScript error. I had to manually put a try-catch around the .submit call within doPostBack to suppress it.
On some pages, a user could perform an action that performs a postback to the same page, but isn't a save. This results in any JavaScript logic resetting, so it thinks nothing has changed after the postback when something may have. I had to implement a hidden textbox that gets posted back with the page, and is used to hold a simple boolean value indicating whether the data is dirty. This gets persisted across postbacks.
You may want some postbacks on the page to not trigger the dialog, such as a Save button. In this case, you can use JQuery to add an OnClick function which sets window.onbeforeunload to null.
Hopefully this is helpful for anyone else who has to implement something similar.
General Solution Supporting multiple forms in a given page (Just copy and paste in your project)
$(document).ready(function() {
$('form :input').change(function() {
$(this).closest('form').addClass('form-dirty');
});
$(window).bind('beforeunload', function() {
if($('form:not(.ignore-changes).form-dirty').length > 0) {
return 'You have unsaved changes, are you sure you want to discard them?';
}
});
$('form').bind('submit',function() {
$(this).closest('form').removeClass('form-dirty');
return true;
});
});
Note: This solution is combined from others' solutions to create a general integrated solution.
Features:
Just copy and paste into your app.
Supports Multiple Forms.
You can style or make actions dirty forms, since they've the class "form-dirty".
You can exclude some forms by adding the class 'ignore-changes'.
The following solution works for prototype (tested in FF, IE 6 and Safari). It uses a generic form observer (which fires form:changed when any fields of the form have been modified), which you can use for other stuff as well.
/* use this function to announce changes from your own scripts/event handlers.
* Example: onClick="makeDirty($(this).up('form'));"
*/
function makeDirty(form) {
form.fire("form:changed");
}
function handleChange(form, event) {
makeDirty(form);
}
/* generic form observer, ensure that form:changed is being fired whenever
* a field is being changed in that particular for
*/
function setupFormChangeObserver(form) {
var handler = handleChange.curry(form);
form.getElements().each(function (element) {
element.observe("change", handler);
});
}
/* installs a form protector to a form marked with class 'protectForm' */
function setupProtectForm() {
var form = $$("form.protectForm").first();
/* abort if no form */
if (!form) return;
setupFormChangeObserver(form);
var dirty = false;
form.observe("form:changed", function(event) {
dirty = true;
});
/* submitting the form makes the form clean again */
form.observe("submit", function(event) {
dirty = false;
});
/* unfortunatly a propper event handler doesn't appear to work with IE and Safari */
window.onbeforeunload = function(event) {
if (dirty) {
return "There are unsaved changes, they will be lost if you leave now.";
}
};
}
document.observe("dom:loaded", setupProtectForm);
Here's a javascript / jquery solution that is simple. It accounts for "undos" by the user, it is encapsulated within a function for ease of application, and it doesn't misfire on submit. Just call the function and pass the ID of your form.
This function serializes the form once when the page is loaded, and again before the user leaves the page. If the two form states are different, the prompt is shown.
Try it out: http://jsfiddle.net/skibulk/Ydt7Y/
function formUnloadPrompt(formSelector) {
var formA = $(formSelector).serialize(), formB, formSubmit = false;
// Detect Form Submit
$(formSelector).submit( function(){
formSubmit = true;
});
// Handle Form Unload
window.onbeforeunload = function(){
if (formSubmit) return;
formB = $(formSelector).serialize();
if (formA != formB) return "Your changes have not been saved.";
};
}
$(function(){
formUnloadPrompt('form');
});
I recently contributed to an open source jQuery plugin called dirtyForms.
The plugin is designed to work with dynamically added HTML, supports multiple forms, can support virtually any dialog framework, falls back to the browser beforeunload dialog, has a pluggable helper framework to support getting dirty status from custom editors (a tinyMCE plugin is included), works within iFrames, and the dirty status can be set or reset at will.
https://github.com/snikch/jquery.dirtyforms
Detect form changes with using jQuery is very simple:
var formInitVal = $('#formId').serialize(); // detect form init value after form is displayed
// check for form changes
if ($('#formId').serialize() != formInitVal) {
// show confirmation alert
}
I expanded on Slace's suggestion above, to include most editable elements and also excluding certain elements (with a CSS style called "srSearch" here) from causing the dirty flag to be set.
<script type="text/javascript">
var _isDirty = false;
$(document).ready(function () {
// Set exclude CSS class on radio-button list elements
$('table.srSearch input:radio').addClass("srSearch");
$("input[type='text'],input[type='radio'],select,textarea").not(".srSearch").change(function () {
_isDirty = true;
});
});
$(window).bind('beforeunload', function () {
if (_isDirty) {
return 'You have unsaved changes.';
}
});
var unsaved = false;
$(":input").change(function () {
unsaved = true;
});
function unloadPage() {
if (unsaved) {
alert("You have unsaved changes on this page. Do you want to leave this page and discard your changes or stay on this page?");
}
}
window.onbeforeunload = unloadPage;
This is exactly what the Fleegix.js plugin fleegix.form.diff (http://js.fleegix.org/plugins/form/diff) was created for. Serialize the initial state of the form on load using fleegix.form.toObject (http://js.fleegix.org/ref#fleegix.form.toObject) and save it in a variable, then compare with the current state using fleegix.form.diff on unload. Easy as pie.
A lot of outdated answers so here's something a little more modern.
ES6
let dirty = false
document.querySelectorAll('form').forEach(e => e.onchange = () => dirty = true)
One method, using arrays to hold the variables so changes can be tracked.
Here's a very simple method to detect changes, but the rest isn't as elegant.
Another method which is fairly simple and small, from Farfetched Blog:
<body onLoad="lookForChanges()" onBeforeUnload="return warnOfUnsavedChanges()">
<form>
<select name=a multiple>
<option value=1>1
<option value=2>2
<option value=3>3
</select>
<input name=b value=123>
<input type=submit>
</form>
<script>
var changed = 0;
function recordChange() {
changed = 1;
}
function recordChangeIfChangeKey(myevent) {
if (myevent.which && !myevent.ctrlKey && !myevent.ctrlKey)
recordChange(myevent);
}
function ignoreChange() {
changed = 0;
}
function lookForChanges() {
var origfunc;
for (i = 0; i < document.forms.length; i++) {
for (j = 0; j < document.forms[i].elements.length; j++) {
var formField=document.forms[i].elements[j];
var formFieldType=formField.type.toLowerCase();
if (formFieldType == 'checkbox' || formFieldType == 'radio') {
addHandler(formField, 'click', recordChange);
} else if (formFieldType == 'text' || formFieldType == 'textarea') {
if (formField.attachEvent) {
addHandler(formField, 'keypress', recordChange);
} else {
addHandler(formField, 'keypress', recordChangeIfChangeKey);
}
} else if (formFieldType == 'select-multiple' || formFieldType == 'select-one') {
addHandler(formField, 'change', recordChange);
}
}
addHandler(document.forms[i], 'submit', ignoreChange);
}
}
function warnOfUnsavedChanges() {
if (changed) {
if ("event" in window) //ie
event.returnValue = 'You have unsaved changes on this page, which will be discarded if you leave now. Click "Cancel" in order to save them first.';
else //netscape
return false;
}
}
function addHandler(target, eventName, handler) {
if (target.attachEvent) {
target.attachEvent('on'+eventName, handler);
} else {
target.addEventListener(eventName, handler, false);
}
}
</script>
In IE document.ready will not work properly it will update the values of input.
so we need to bind load event inside the document.ready function that will handle for IE browser also.
below is the code you should put inside the document.ready function.
$(document).ready(function () {
$(window).bind("load", function () {
$("input, select").change(function () {});
});
});
I have found that this one works in Chrome with an exception... The messages being returned do not match those in the script:
dataChanged = 0; // global variable flags unsaved changes
function bindForChange() {
$("input,checkbox,textarea,radio,select").bind("change", function (_event) {
dataChanged = 1;
});
$(":reset,:submit").bind("click", function (_event) {
dataChanged = 0;
});
}
function askConfirm() {
if (dataChanged) {
var message =
"You have some unsaved changes. Press OK to continue without saving.";
return message;
}
}
window.onbeforeunload = askConfirm;
window.onload = bindForChange;
The messages returned seem to be triggered by the specific type of action I'm performing. A RELOAD displays a question "Reload Site?
And a windows close returns a "Leave Site?" message.