Develop Reference

Is there any way to get the function in specific event be triggered? [duplicate]

I need to find which event handlers are registered over an object.
For example:
$("#el").click(function() {...});
$("#el").mouseover(function() {...});
$("#el") has click and mouseover registered.
Is there a function to find out that, and possibly iterate over the event handlers?
If it is not possible on a jQuery object through proper methods, is it possible on a plain DOM object?

As of jQuery 1.8, the event data is no longer available from the "public API" for data. Read this jQuery blog post. You should now use this instead:
jQuery._data( elem, "events" );
elem should be an HTML Element, not a jQuery object, or selector.
Please note, that this is an internal, 'private' structure, and shouldn't be modified. Use this for debugging purposes only.
In older versions of jQuery, you might have to use the old method which is:
jQuery( elem ).data( "events" );

You can do it by crawling the events (as of jQuery 1.8+), like this:
$.each($._data($("#id")[0], "events"), function(i, event) {
// i is the event type, like "click"
$.each(event, function(j, h) {
// h.handler is the function being called
});
});
Here's an example you can play with:
$(function() {
$("#el").click(function(){ alert("click"); });
$("#el").mouseover(function(){ alert("mouseover"); });
$.each($._data($("#el")[0], "events"), function(i, event) {
output(i);
$.each(event, function(j, h) {
output("- " + h.handler);
});
});
});
function output(text) {
$("#output").html(function(i, h) {
return h + text + "<br />";
});
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="el">Test</div>
<code>
<span id="output"></span>
</code>

For jQuery 1.8+, this will no longer work because the internal data is placed in a different object.
The latest unofficial (but works in previous versions as well, at least in 1.7.2) way of doing it now is -
$._data(element, "events")
The underscore ("_") is what makes the difference here. Internally, it is calling $.data(element, name, null, true), the last (fourth) parameter is an internal one ("pvt").

Shameless plug, but you can use findHandlerJS
To use it you just have to include findHandlersJS (or just copy&paste the raw javascript code to chrome's console window) and specify the event type and a jquery selector for the elements you are interested in.
For your example you could quickly find the event handlers you mentioned by doing
findEventHandlers("click", "#el")
findEventHandlers("mouseover", "#el")
This is what gets returned:
element
The actual element where the event handler was registered in
events
Array with information about the jquery event handlers for the event type that we are interested in (e.g. click, change, etc)
handler
Actual event handler method that you can see by right clicking it and selecting Show function definition
selector
The selector provided for delegated events. It will be empty for direct events.
targets
List with the elements that this event handler targets. For example, for a delegated event handler that is registered in the document object and targets all buttons in a page, this property will list all buttons in the page. You can hover them and see them highlighted in chrome.
You can try it here

I use eventbug plugin to firebug for this purpose.

I've combined both solutions from #jps to one function:
jQuery.fn.getEvents = function() {
if (typeof(jQuery._data) === 'function') {
return jQuery._data(this.get(0), 'events') || {};
}
// jQuery version < 1.7.?
if (typeof(this.data) === 'function') {
return this.data('events') || {};
}
return {};
};
But beware, this function can only return events that were set using jQuery itself.

To check for events on an element:
var events = $._data(element, "events")
Note that this will only work with direct event handlers, if you are using $(document).on("event-name", "jq-selector", function() { //logic }), you will want to see the getEvents function at the bottom of this answer
For example:
var events = $._data(document.getElementById("myElemId"), "events")
or
var events = $._data($("#myElemId")[0], "events")
Full Example:
<html>
<head>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.0/jquery.min.js" type="text/javascript"></script>
<script>
$(function() {
$("#textDiv").click(function() {
//Event Handling
});
var events = $._data(document.getElementById('textDiv'), "events");
var hasEvents = (events != null);
});
</script>
</head>
<body>
<div id="textDiv">Text</div>
</body>
</html>
A more complete way to check, that includes dynamic listeners, installed with $(document).on
function getEvents(element) {
var elemEvents = $._data(element, "events");
var allDocEvnts = $._data(document, "events");
for(var evntType in allDocEvnts) {
if(allDocEvnts.hasOwnProperty(evntType)) {
var evts = allDocEvnts[evntType];
for(var i = 0; i < evts.length; i++) {
if($(element).is(evts[i].selector)) {
if(elemEvents == null) {
elemEvents = {};
}
if(!elemEvents.hasOwnProperty(evntType)) {
elemEvents[evntType] = [];
}
elemEvents[evntType].push(evts[i]);
}
}
}
}
return elemEvents;
}
Example usage:
getEvents($('#myElemId')[0])

As of 1.9 there is no documented way to retrieve the events, other than to use the Migrate plugin to restore the old behavior. You could use the _.data() method as jps mentions, but that is an internal method. So just do the right thing and use the Migrate plugin if you need this functionality.
From the jQuery documentation on .data("events")
Prior to 1.9, .data("events") could be used to retrieve jQuery's
undocumented internal event data structure for an element if no other
code had defined a data element with the name "events". This special
case has been removed in 1.9. There is no public interface to retrieve
this internal data structure, and it remains undocumented. However,
the jQuery Migrate plugin restores this behavior for code that depends
upon it.

I created a custom jQuery selector that checks against both jQuery's cache of assigned event handlers as well as elements that use the native method for adding them:
(function($){
$.find.selectors[":"].event = function(el, pos, match) {
var search = (function(str){
if (str.substring(0,2) === "on") {str = str.substring(2);}
return str;
})(String(match[3]).trim().toLowerCase());
if (search) {
var events = $._data(el, "events");
return ((events && events.hasOwnProperty(search)) || el["on"+search]);
}
return false;
};
})(jQuery);
Example:
$(":event(click)")
This will return elements that have a click handler attached to them.

In a modern browser with ECMAScript 5.1 / Array.prototype.map, you can also use
jQuery._data(DOCUMENTELEMENT,'events')["EVENT_NAME"].map(function(elem){return elem.handler;});
in your browser console, which will print the source of the handlers, comma delimited. Useful for glancing at what all is running on a particular event.

Events can be retrieved using:
jQuery(elem).data('events');
or jQuery 1.8+:
jQuery._data(elem, 'events');
Note:
Events bounded using $('selector').live('event', handler)
can be retrieved using:
jQuery(document).data('events')

jQuery is not letting you just simply access the events for a given element.
You can access them using undocumented internal method
$._data(element, "events")
But it still won't give you all the events, to be precise won't show you events assigned with
$([selector|element]).on()
These events are stored inside document, so you can fetch them by browsing through
$._data(document, "events")
but that is hard work, as there are events for whole webpage.
Tom G above created function that filters document for only events of given element and merges output of both methods, but it had a flaw of duplicating events in the output (and effectively on the element's jQuery internal event list messing with your application).
I fixed that flaw and you can find the code below. Just paste it into your dev console or into your app code and execute it when needed to get nice list of all events for given element.
What is important to notice, element is actually HTMLElement, not jQuery object.
function getEvents(element) {
var elemEvents = $._data(element, "events");
var allDocEvnts = $._data(document, "events");
function equalEvents(evt1, evt2)
{
return evt1.guid === evt2.guid;
}
for(var evntType in allDocEvnts) {
if(allDocEvnts.hasOwnProperty(evntType)) {
var evts = allDocEvnts[evntType];
for(var i = 0; i < evts.length; i++) {
if($(element).is(evts[i].selector)) {
if(elemEvents == null) {
elemEvents = {};
}
if(!elemEvents.hasOwnProperty(evntType)) {
elemEvents[evntType] = [];
}
if(!elemEvents[evntType].some(function(evt) { return equalEvents(evt, evts[i]); })) {
elemEvents[evntType].push(evts[i]);
}
}
}
}
}
return elemEvents;
}

I have to say many of the answers are interesting, but recently I had a similar problem and the solution was extremely simple by going the DOM way. It is different because you don't iterate but aim directly at the event you need, but below I'll give a more general answer.
I had an image in a row:
<table>
<td><tr><img class="folder" /></tr><tr>...</tr></td>
</table>
And that image had a click event handler attached to it:
imageNode.click(function () { ... });
My intention was to expand the clickable area to the whole row, so I first got all images and relative rows:
tableNode.find("img.folder").each(function () {
var tr;
tr = $(this).closest("tr");
// <-- actual answer
});
Now in the actual anwer line I just did as follows, giving an answer to the original question:
tr.click(this.onclick);
So I fetched the event handler directly from the DOM element and put it into the jQuery click event handler. Works like a charm.
Now, to the general case. In the old pre-jQuery days you could get all events attached to an object with two simple yet powerful functions gifted to us mortals by Douglas Crockford:
function walkTheDOM(node, func)
{
func(node);
node = node.firstChild;
while (node)
{
walkTheDOM(node, func);
node = node.nextSibling;
}
}
function purgeEventHandlers(node)
{
walkTheDOM(node, function (n) {
var f;
for (f in n)
{
if (typeof n[f] === "function")
{
n[f] = null;
}
}
});
}

Try jquery debugger plugin if you're using chrome: https://chrome.google.com/webstore/detail/jquery-debugger/dbhhnnnpaeobfddmlalhnehgclcmjimi?hl=en

Another way to do it is to just use jQuery to grab the element, then go through actual Javascript to get and set and play with the event handlers. For instance:
var oldEventHandler = $('#element')[0].onclick;
// Remove event handler
$('#element')[0].onclick = null;
// Switch it back
$('#element')[0].onclick = oldEventHandler;

I combined some of the answers above and created this crazy looking but functional script that lists hopefully most of the event listeners on the given element. Feel free to optimize it here.
var element = $("#some-element");
// sample event handlers
element.on("mouseover", function () {
alert("foo");
});
$(".parent-element").on("mousedown", "span", function () {
alert("bar");
});
$(document).on("click", "span", function () {
alert("xyz");
});
var collection = element.parents()
.add(element)
.add($(document));
collection.each(function() {
var currentEl = $(this) ? $(this) : $(document);
var tagName = $(this)[0].tagName ? $(this)[0].tagName : "DOCUMENT";
var events = $._data($(this)[0], "events");
var isItself = $(this)[0] === element[0]
if (!events) return;
$.each(events, function(i, event) {
if (!event) return;
$.each(event, function(j, h) {
var found = false;
if (h.selector && h.selector.length > 0) {
currentEl.find(h.selector).each(function () {
if ($(this)[0] === element[0]) {
found = true;
}
});
} else if (!h.selector && isItself) {
found = true;
}
if (found) {
console.log("################ " + tagName);
console.log("event: " + i);
console.log("selector: '" + h.selector + "'");
console.log(h.handler);
}
});
});
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="parent-element">
<span id="some-element"></span>
</div>

jQuery off() is not unbinding events when using bind

function bubble(content, triggerElm){
this.element = $('<div class="bubble" />').html(content);
this.element.css(.....) // here is positioned based on triggerElm
}
bubble.prototype.show = function(){
$(document).on('click', this._click.bind(this));
this.element.css(....)
};
bubble.prototype.hide = function(){
$(document).off('click', this._click.bind(this));
this.element.css(....)
};
bubble.prototype._click = function(event){
console.log('click', this);
if(this.element.is(event.target) || (this.element.has(event.target).length > 0))
return true;
this.hide();
};
var b = new bubble();
b.show();
b.hide();
I keep seeing click in the console, so the click does not unbind.
But if I remove the bind() call the click is unbinded. Does anyone know why? I need a way to be able to change "this" inside my test function, that's why I'm using bind().

The problem is that this._click.bind() creates a new function every time it's called. In order to detach a specific event handler, you need to pass in the original function that was used to create the event handler and that's not happening here, so the handler is not removed.
If there are only going to be a few bubbles in your app, you could and simply not use this. That will remove a lot of the confusion about what this is referring to and ensure that each bubble retains a reference to its own click function that can be used to remove the event as needed:
function bubble(content, triggerElm) {
var element = $('<div class="bubble" />').html(content);
element.css(.....); // here is positioned based on triggerElm
function click(event) {
console.log('click', element);
if (element.is(event.target) ||
element.has(event.target).length > 0) {
return true;
}
hide();
}
function show() {
$(document).on('click', click);
element.css(....);
}
function hide() {
$(document).off('click', click);
element.css(....);
}
return {
show: show,
hide: hide
};
}
var b1 = bubble(..., ...);
b1.show();
var b2 = bubble(..., ...);
b2.show();
See how this frees you from using contrivances like .bind() and underscore-prefixed methods.

One option would be to namespace the event:
$(document).on('click.name', test.bind(this));
$(document).off('click.name');
Example Here

try use jQuery's proxy to get a unique reference of your function.
In this way, when you call $.proxy(test, this), it will check if this function has already been referenced before. If yes, proxy will return you that reference, otherwise it will create one and return it to you. So that, you can always get your original function, rather than create it over and over again (like using bind).
Therefore, when you call off(), and pass it the reference of your test function, off() will remove your function from click event.
And also, your test function should be declared before use it.
var test = function(){
console.log('click');
};
$(document).on('click', $.proxy(test, this));
$(document).off('click', $.proxy(test, this));
http://jsfiddle.net/aw50yj7f/

Please read https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind
bind creates a new function therefore doing $(document).on('click', test.bind(this)); is like $(document).on('click', function(){}); and each time you execute it you invoke a new anonymous function thus you dont have a reference to unbind.
If you would do something like:
var test = function(){
console.log('click');
};
var newFunct = test.bind(this);
$(document).on('click', newFunct );
$(document).off('click', newFunct );
It should work fine
e.g: http://jsfiddle.net/508dr0hv/
Also - using bind is not recommended, its slow and not supported in some browsers.

rather than binding this to the event, send this as a parameter:
$("#DOM").on("click",{
'_this':this
},myFun);
myFun(e){
console.info(e.data._this);
$("#DOM").off("click",myFun);
}

jQuery callbacks cumulation

I'm building a simple jQuery plugin called magicForm (How ridiculous is this?). Now face to a problem that I think I'm not figuring out properly.
My plugin is supposed to be applied on a container element, that will show each of its inputs one by one as user fills them. That's not the exact purpose of my problem.
Each time I initialize the container, I declare an event click callback. Let me show an example.
(function($){
var methods = {
init: function(options){
return this.each(function(){
var form, inputs;
var settings = {
debug: false
};
settings = $.extend(settings, options);
form = $(this);
$('a.submit', form).on('click', function(event){
if (settings.submitCallback) {
settings.submitCallback.call(form, inputs);
}
return false;
});
});
},
reset: function() {
}
}
$.fn.magicForm = function(method) {
if ( methods[method] ) {
return methods[ method ].apply( this, Array.prototype.slice.call( arguments, 1 ));
} else if ( typeof method === 'object' || ! method ) {
return methods.init.apply( this, arguments );
} else {
$.error( 'Method ' + method + ' does not exist.' );
}
};
})($);
I'm focusing on a specific part of this code :
$('a.submit', form).on('click', function(event){
if (settings.submitCallback) {
settings.submitCallback.call(form, inputs);
}
return false;
});
Because each time the init method is called, that poor callback is registered.
I was experiencing this painfully, when I invoked my plugin on an element nested in a twitter bootstrap 'tab', nested itself in a bootstrap modal :
I was calling init each time the event 'shown' of my bootstrap modal was triggered.
So, this is how I fixed it in my init method :
// Prevent callback cumulation
if (!$(this).data('form_initialized')) {
$('a.submit', form).on('click', function(event){
if (settings.submitCallback) {
settings.submitCallback.call(form, inputs);
}
return false;
});
$(this).data('form_initialized', true);
}
And I'm far from feeling sure about this.
Thank your for your time !

Many jquery plugins use data to know if their plugins were initialized. Most often, they use the name of their own plugin as a part (or in whole) as the data. For example:
$(this).data('magicForm')
So your approach of using that to signal is not a bad one.
However, you have two other options:
1) Pull the event handler out so the handler is a single instance. Above your methods, do var fnOnSubmit = function() { ... } Then you can simply ensure proper binding by calling $('a.submit', form).unbind('click', fnOnSubmit) before rebinding it the way you are already doing it.
2) Another option is to use event namespaces.
$('a.submit', form).unbind('click.magicForm'); then rebinding it with .on('click.magicForm') This namespace approach ensures that when you unbind it only unbinds in the context of your namespace magicForm, thus leaving all other click events (e.g. from other plugins) intact.
I hope this helps.

You could first explicitely remove the click-handler:
$('a.submit', form).off('click').on('click', function(event){ ... })
However, I would suggest you use event namespacing to prevent all click handlers (even those perhaps set by code not your own) from being removed:
$('a.submit', form).off('click.magicForm').on('click.magicForm', function(event){ ... })

Bind to custom CSS animation end event with jQuery or JavaScript?

We have multiple animations against the same object. We need to take different actions when each of these animations end.
Right now, we bind to the webkitAnimationEnd event, and use a gnarly if/then statement to handle each animation differently.
Is there a way to essentially create custom webkitAnimationEnd events, allowing us to fire a specific event handler when a specific animation ends? For instance, fire handler1 when animation1 ends and fire handler2 when animation2 ends.
We're building for Webkit browsers, specifically Mobile Safari.
Thanks!

For a simple event-trigger, you can pass a function to jQuery's trigger() method and use the returned value of that function to call a trigger a specific event (which can then be listened-for:
function animEndTrigger(e) {
if (!e) {
return false;
}
else {
var animName = e.originalEvent.animationName;
return animName + 'FunctionTrigger';
}
}
$('body').on('bgAnimFunctionTrigger fontSizeFunctionTrigger', function(e){
console.log(e);
});
$('div').on('webkitAnimationEnd', function(e) {
$(this).trigger(animEndTrigger(e));
});
JS Fiddle demo.
You can, of course, also use the called function to either trigger the event itself or assess the passed parameters to determine whether or not to return an event at all:
One method to assess for a particular event to trigger is to use an object:
var animations = {
'bgAnim': 'aParticularEvent'
};
function animEndTrigger(e) {
if (!e) {
return false;
}
else {
var animName = e.originalEvent.animationName;
return animations[animName] ? animations[animName] : false;
}
}
$('body').on('aParticularEvent', function(e) {
console.log(e);
});
$('div').on('webkitAnimationEnd', function(e) {
$(this).trigger(animEndTrigger(e));
});​
JS Fiddle demo.
Though, in this case, the return false should be altered so as not to provide the error Uncaught TypeError: Object false has no method 'indexOf' (which I've not bothered, as yet, to account for).
The following causes the called-function (animEndTrigger()) to directly trigger() the custom event (which requires an element on which to bind the trigger() method) and also avoids the Uncaught TypeError above:
var animations = {
'bgAnim': 'aParticularEvent'
};
function animEndTrigger(e, el) {
if (!e || !el) {
return false;
}
else {
var animName = e.originalEvent.animationName;
if (animations[animName]) {
$(el).trigger(animations[animName]);
}
}
}
$('body').on('aParticularEvent', function(e) {
console.log(e);
});
$('div').on('webkitAnimationEnd', function(e) {
animEndTrigger(e, this);
});​
JS Fiddle demo.
Of course you're still, effectively, using an if to perform an assessment, so I can't be particularly sure that this is any tidier than your own already-implemented solution.

Using unbind, I receive a Javascript TypeError: Object function has no method 'split'

I've written this code for a friend. The idea is he can add a "default" class to his textboxes, so that the default value will be grayed out, and then when he clicks it, it'll disappear, the text will return to its normal color, and then clicking a second time won't clear it:
$(document).ready(function() {
var textbox_click_handler = function clear_textbox() {
$(this).removeClass('default');
$(this).attr('value', '');
$(this).unbind(textbox_click_handler);
};
$(".default").mouseup(textbox_click_handler);
});
The clicking-to-clear works, but I get the following error:
Uncaught TypeError: Object function clear_textbox() { ... } has no method 'split'
what is causing this? How can I fix it? I would just add an anonymous function in the mouseup event, but I'm not sure how I would then unbind it -- I could just unbind everything, but I don't know if he'll want to add more functionality to it (probably not, but hey, he might want a little popup message to appear when certain textboxes are clicked, or something).
How can I fix it? What is the 'split' method for? I'm guessing it has to do with the unbind function, since the clearing works, but clicking a second time still clears it.

You can do it like this:
var textbox_click_handler = function(e) {
$(this).removeClass('default')
.attr('value', '')
.unbind(e.type, arguments.callee);
};
$(function() {
$(".default").mouseup(textbox_click_handler);
});
Or use the .one function instead that automatically unbinds the event:
$(function() {
$(".default").one('mouseup', function() {
$(this).removeClass('default').attr('value', '');
});
});

The unbind needs an event handler while you are specifying a function to its argument thereby giving you the error.

I am not sure if this is really different but try assigning the function to a variable:
var c = function clear_textbox() {
$(this).removeClass('default');
$(this).attr('value', '');
$(this).unbind('mouseup');
}
and then:
$(".default").mouseup(function(){
c();
});

if you don't want to completely unbind mouseup, check for the current state using hasClass(). No need to unbind anything.
$(document).ready(function() {
$('.default').bind('mouseup', function(e) {
var tb = $(this);
if(tb.hasClass('default')) {
tb.removeClass('default').val('');
}
});
});

Make sure you are unbinding mouseup:
function clear_textbox() {
$(this).removeClass('default');
$(this).attr('value', '');
$(this).unbind('mouseup');
}
$(function() {
$('.default').mouseup(clear_textbox);
});
Also I would write this as a plugin form:
(function($) {
$.fn.watermark = function(settings) {
this.each(function() {
$(this).css('color', 'gray');
$(this).mouseup(function() {
var $this = $(this);
$this.attr('value', '');
$this.unbind('mouseup');
});
});
return this;
};
})(jQuery);
so that your friend can simply:
$(function() {
$('.someClassYourFriendUses').watermark();
});