JQuery trigger element itself in a bind - javascript

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

Related

Re-enabling event.preventDefault();

I have been searching for ages for a solution to this problem, I am aware that there is no restore default solution type of thing. However here is my problem.
$('#signInbtn').click(function(event) {
checkLogInForm(event);
});
this checks the login in fields to confirm they are not left blank, like so:
function checkLogInForm(event) {
var usernameValid, passwordValid = false;
checkUsername(usernameValid);
checkPassword(passwordValid);
if (!passwordValid || !usernameValid) {
event.preventDefault();
} else {
$('#signInbtn').unbind('submit');
}
}
However the numerous solutions I have tried never result in the form actually submitting when the else is triggered. Any ideas how I can resume/submit the default behaviour? or even an alternative approach. Thanks for any help!
fiddle
One solution would be to evaluate whether the preventDefault action should be applied:
/**
* toggle status if preventDefaultStatus is true
*/
function updateStatus(preventDefaultStatus) {
return (preventDefaultStatus === true) ? false : true;
}
/**
* toggle preventDefault
*/
function toggleDefault(isActive) {
submitElement.onclick = function(e){
if(isActive === true){
e.preventDefault();
}
}
}
/**
* trigger toggleDefault and updateStatus
*/
function update(){
toggleDefault(status);
status = updateStatus(status);
}
exampleButton.onclick = update;
(function(){
update();
})();
(written in pure javascript to clarify that this applies regardless of whether or not you're using jQuery)
In jQuery, you would just replace the onclick handlers with .click(function(e){})
Try using the 'submit' event with the form id or form name as the jQuery selector for example:
$('#signInForm').submit(function(event) {
checkLogInForm(event);
});
Your checkLogInForm(event) method can leave the else statement out if the form should be submitted.

Why Internet Explorer stop after a function when use event.preventDefault() or return false

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

Preserving current click event jquery

I need to temporarily change the click event for an element as follows:
var originalEvent = '';
$("#helpMode").click(function (e) {
originalEvent = $("#element").getCurrentClickEventHandler();
$("#element").click(function (e) {
//Do something else
});
});
//Later in the code
$("#helpModeOff").click(function (e) {
$("#element").click(originalEvent);
});
How would I store the current function that is an event handler in a global variable for later reuse?
EDIT: Here's what im trying to do:
var evnt = '';
$("#helpTool").click(function (e) {
if(!this.isOn){
evnt = $("#Browse").data('events').click;
$("#ele").unbind('click');
$("#ele").click(function (e) {
alert('dd');
});
this.isOn=true;
}else{
this.isOn = false;
alert('off');
$("#ele").unblind('click');
$("#ele").click(evnt);
}
});
Here you go, figured it out:
Now with e.srcElement.id you can get either HelpMode or HelpModeOff and then can turn on/off your help stuff!
http://jsfiddle.net/zcDQ9/1/
var originalEvent = '';
$('#element').on('yourCustomEvent', function (e) {
// do stuff
alert(originalEvent);
$(this).toggleClass('toggleThing');
//test for helpMode or helpModeOff here now...
});
$("#helpMode").on('click', function (e) {
originalEvent = e.srcElement.id;
$("#element").trigger('yourCustomEvent');
});
//Later in the code
$("#helpModeOff").on('click', function (e) {
originalEvent = e.srcElement.id;
$("#element").trigger('yourCustomEvent');
});​
Okay. In jQuery 1.7 I guess it's a little different.
//get the handler from data('events')
$.each($("#element").data("events"), function(i, event) {
if (i === "click") {
$.each(event, function(j, h) {
alert(h.handler);
});
}
});
http://jsfiddle.net/yQwZU/
This is the reference.
Not sure if the following works with 1.7.
originalEvent = $('#element').data('events').click;
jQuery stored all the handlers in data. See here to learn more about data('events').
Personally, I think I would avoid manually binding and unbinding handlers.
Another way to approach this is to bind click events to classes, then all you need to do is add and remove classes from the appropriate elements when switching to/from help mode.
Here's a jsfiddle illustrating what I mean.
Switching to and from help mode then just involves adding removing classes:
$('#btnhelpmode').click(function(){
if(!helpMode){
helpMode = true;
$('.normalmode').addClass('helpmode').removeClass('normalmode');
$(this).val('Switch to normal mode...');
}else{
helpMode = false;
$('.helpmode').addClass('normalmode').removeClass('helpmode');
$(this).val('Switch to help mode...');
}
});
and you just create the handlers required, binding them to the appropriate classes:
$('#pagecontent').on('click', '#element1.normalmode', function(){
alert('element1 normal mode');
});
$('#pagecontent').on('click', '#element1.helpmode', function(){
alert('element1 help mode');
});
$('#pagecontent').on('click', '#element2.normalmode', function(){
alert('element2 normal mode');
});
$('#pagecontent').on('click', '#element2.helpmode', function(){
alert('element2 help mode');
});

Stop further event handlers on an element

I'm writing a little jQuery extension that prevents a user from double clicking on a link.
$.fn.preventDoubleClick = function() {
return this.click(function() {
var $t = $(this)
, retVal = $t.data('active') // check the internal flag
;
if (retVal || retVal === undefined) { // if ON...
$t.data('active', false); // set the internal flag to OFF
setTimeout(function() {
$t.data('active', true);
}, 1000); // after 1 second, set the internal flag to ON
console.log("allowed");
return true;
} else { // if OFF...
console.log("blocked");
return false;
}
});
};
the problem is that if there are other click event handlers on the elements, they still fire:
$('#myLink').click(function() {
console.log("Clicked");
});
$('#myLink').preventDoubleClick();
And now when you double click the link, I get this in my log:
allowed
clicked
blocked
clicked
So basically, I need the click function inside preventDoubleClick to stop all the other event handlers from firing. How can I do this?
Thanks to Adam's link, I was able to see the function I needed: stopImmediatePropagation().
I believe you're looking for event.stopPropagation
EDIT: turns out this was not the correct option for Nick's purposes. Please see his answer.

Detecting Unsaved Changes

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.

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