Comparing jQuery (javascript?) Events for Equal Origin Click - javascript

I'm comparing click events in jQuery to see if they fired from the same click. Right now I'm using the events' timeStamp to test to see if the events came from the same click, and while this will almost certainly work, I'm wondering if there's a better way.
For example, if body and header both have a click event, and I click on the header, it will bubble up to the body. What is the best way to test if both events that fire come from the same click?

In plain JavaScript, the same event object will reach both event listeners, so you can compare them. jQuery on the other hand will wrap the original event object into a new normalized object for each listener, so you have to check their .originalEvent property instead.
In any case, I never needed to check for that. Usually, you just want to know if the clicked element is the same as the one you bound the click to, or not:
document.body.addEventListener('click', function(e) {
if(e.target === this) {
// the click happened on the body itself
} else {
// the click bubbled up
}
}, false);
jQuery provides a nice mechanism for event delegation, so you don't even need the if:
$('body').on('click', '.someSelector', function(e) {
// This will only fire if an element with class 'someSelector'
// was clicked
});

Related

javascript/jquery How to cancel .on when a class is present

I have several places throughout my code where I use .on to attach events (usually to delegate the events). We're changing around how we're doing a few things, and we're now wanting to add a .disabled class to the elements that we want to be disabled. I'd like to block all the events on disabled items without having to refactor each location, I'm wondering if it's possible.
Example code: I've added this to the top of my script
$('body').on('click', '.disabled', function(event){
console.log("blocked");
event.stopImmediatePropagation();
// event.preventDefault();
// event.stopPropogation();
return false;
});
And an example of my normal events:
$('.ActionsContainer').on('click', '.Link', functions.ClickAction);
Problem is that even with the return false and all the others it still runs both the "blocked" and functions.ClickAction
Is there anyway around refactoring every one? I mean I can change that line below to:
$('.ActionsContainer').on('click', '.Link:not(.disabled)', functions.ClickAction);
but that's really annoying, and feels brittle.
It's not too hard. You'll need to take advantage of jQuery's special events and basically override calls to any of the original event handlers setup in the existing code. jQuery's special events hooks let you override a number of features of the event system. jQuery essentially sets up it's own handler on an element the first time a listener is attached, and then adds the callback for the listener to its queue. As other listeners get attached to the element later, their callbacks get added to this queue as well.
Using the 'events.special.click' hook, we can add a function that gets called prior to any callbacks on that element's event queue which lets us intercept the call and check for, as you mentioned, that the element has a 'disabled' class and if so, stop the original callback from executing; or if it doesn't have the class, allow the original callback to execute normally.
I've put together a jsFiddle to show how it works. See if that solves your issue. The code for the override using special events is embedded below the link:
http://jsfiddle.net/datchley/bthcv/
// ADDED TO OVERRIDE CLICKS ON 'DISABLED' ELEMENTS
(function($) {
$.event.special.click = {
add: function(handle) {
// Save original handler
var orig_handlefn = handle.handler,
$el = $(this);
// Reassign our new handler to intercept here
handle.handler = function(ev) {
if ($el.hasClass('disabled')) {
// Don't allow clicks on disabled elements
$('.output').html('<b>Warning</b> You clicked a disabled element!');
ev.preventDefault();
}
else {
return orig_handlefn.apply(this, arguments);
}
};
}
};
})(jQuery);
Assuming every .Link has that container and you're handling all events at that container, this is the most straightforward way:
$('.disabled').click( function(e){ e.stopPropagation(); } );
stopProp prevents that event from ever bubbling up to the action containers.

How to make all page elements not to react on clicks

I'm trying to make an extension with 'pick' functionality: letting the user click on any element on the page and see the xpath for it.
However, to make it usable I have to prevent the element from reacting on clicking: I don't want clicking on hyperlinks to forward me to another page, buttons to submit forms, etc., etc.
How would I do that?
UPD: I need it only for Chrome
The cleanest way in my opinion would be to bind one event handler to body in the capturing phase and prevent the event from propagating/the default behavior.
You can get a reference to the clicked element with event.target:
document.body.addEventListener('click', function(event) {
event.preventDefault();
event.stopPropagation();
console.log(event.target);
}, true);
The advantage is that this event handler will be the very first that is triggered, no matter which other event handlers are bound to elements in the page (unless of course the page binds a similar event handler to body, but usually event handlers are bound in the bubbling phase).
For more information see quirksmode.org - Event order and MDN - addEventListener.
DEMO
For a CSS only solution:
* {
pointer-events: none;
}
Try this
$('body *').on('click',function(e){
return false;
});
In your click event handler make sure you either call preventDefault() in the event object, or return false from your function. For example:
function myClickHandler(e) {
e.preventDefault() // e is the event object
// Do your click stuff here
.
.
.
return false; // not required if you've called e.preventDefault()
}

How do I handle a click anywhere in the page, even when a certain element stops the propagation?

We are working on a JavaScript tool that has older code in it,
so we cannot re-write the whole tool.
Now, a menu was added position fixed to the bottom and the client would very much like it to have a toggle button to open and close the menu,
except closing needs to happen automatically when a user starts doing things out side of the menu, for example, when a user goes back into the page, and selects something or clicks on a form field.
This could technically work with a click event on the body, triggering on any click,
however there are numerous items in the older code, where a click event was handled on an internal link, and return false was added to the click function, in order for the site not to continue to the link's href tag.
So clearly, a general function like this does work, but not when clicked on an internal link where the return false stops the propagation.
$('body').click(function(){
console.log('clicked');
});
Is there a way I can force the body click event anyway,
or is there another way I can let the menu dissappear, using some global click event or anything similar?
Without having to rewrite all other clicks in the application that were created years ago.
That would be a monster task, especially since I have no clue how I would rewrite them, without the return false, but still don't let them go to their href.
Events in modern DOM implementations have two phases, capturing and bubbling. The capturing phase is the first phase, flowing from the defaultView of the document to the event target, followed by the bubbling phase, flowing from the event target back to the defaultView. For more information, see http://www.w3.org/TR/DOM-Level-3-Events/#event-flow.
To handle the capturing phase of an event, you need to set the third argument for addEventListener to true:
document.body.addEventListener('click', fn, true);
Sadly, as Wesley mentioned, the capturing phase of an event cannot be handled reliably, or at all, in older browsers.
One possible solution is to handle the mouseup event instead, since event order for clicks is:
mousedown
mouseup
click
If you can be sure you have no handlers cancelling the mouseup event, then this is one way (and, arguably, a better way) to go. Another thing to note is that many, if not most (if not all), UI menus disappear on mouse down.
In cooperation with Andy E, this is the dark side of the force:
var _old = jQuery.Event.prototype.stopPropagation;
jQuery.Event.prototype.stopPropagation = function() {
this.target.nodeName !== 'SPAN' && _old.apply( this, arguments );
};
Example: http://jsfiddle.net/M4teA/2/
Remember, if all the events were bound via jQuery, you can handle those cases just here. In this example, we just call the original .stopPropagation() if we are not dealing with a <span>.
You cannot prevent the prevent, no.
What you could do is, to rewrite those event handlers manually in-code. This is tricky business, but if you know how to access the stored handler methods, you could work around it. I played around with it a little, and this is my result:
$( document.body ).click(function() {
alert('Hi I am bound to the body!');
});
$( '#bar' ).click(function(e) {
alert('I am the span and I do prevent propagation');
e.stopPropagation();
});
$( '#yay' ).click(function() {
$('span').each(function(i, elem) {
var events = jQuery._data(elem).events,
oldHandler = [ ],
$elem = $( elem );
if( 'click' in events ) {
[].forEach.call( events.click, function( click ) {
oldHandler.push( click.handler );
});
$elem.off( 'click' );
}
if( oldHandler.length ) {
oldHandler.forEach(function( handler ) {
$elem.bind( 'click', (function( h ) {
return function() {
h.apply( this, [{stopPropagation: $.noop}] );
};
}( handler )));
});
}
});
this.disabled = 1;
return false;
});
Example: http://jsfiddle.net/M4teA/
Notice, the above code will only work with jQuery 1.7. If those click events were bound with an earlier jQuery version or "inline", you still can use the code but you would need to access the "old handler" differently.
I know I'm assuming a lot of "perfect world" scenario things here, for instance, that those handles explicitly call .stopPropagation() instead of returning false. So it still might be a useless academic example, but I felt to come out with it :-)
edit: hey, return false; will work just fine, the event objects is accessed in the same way.
this is the key (vs evt.target). See example.
document.body.addEventListener("click", function (evt) {
console.dir(this);
//note evt.target can be a nested element, not the body element, resulting in misfires
console.log(evt.target);
alert("body clicked");
});
<h4>This is a heading.</h4>
<p>this is a paragraph.</p>
If you make sure that this is the first event handler work, something like this might do the trick:
$('*').click(function(event) {
if (this === event.target) { // only fire this handler on the original element
alert('clicked');
}
});
Note that, if you have lots of elements in your page, this will be Really Very Slow, and it won't work for anything added dynamically.
What you really want to do is bind the event handler for the capture phase of the event. However, that isn't supported in IE as far as I know, so that might not be all that useful.
http://www.quirksmode.org/js/events_order.html
Related questions:
jQuery equivalent of JavaScript's addEventListener method
Emulate W3C event capturing model in IE
I know this is an old question, but to add to #lonesomeday's answer, you can do the same in vanilla JavaScript with:
document.querySelectorAll('*')
.forEach(element => element.addEventListener('click', e => {
console.log('clicked: ', e.target)
}))
This will add the listener to each element instead of to the body, and from experience this will let you execute the click event even if the page is navigating away or if there's already an onclick with stopPropagation in it.
I think this is what you need:
$("body").trigger("click");
This will allow you to trigger the body click event from anywhere.
You could use jQuery to add an event listener on the document DOM.
$(document).on("click", function () {
console.log('clicked');
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
document.body.addEventListener("keyup", function(event) {
if (event.keyCode === 13) {
event.preventDefault();
console.log('clicked ;)');
}
});
DEMO
https://jsfiddle.net/muratkezli/51rnc9ug/6/
My fix in Feb 2023:
To trigger a function anywhere on the page/document:
JS code:
document.onmouseup = closeMenus
'closeMenus' would be a function that turns each menu's display value to none.
Any 'mouseup' event anywhere on the document, calls the function.

Override all JavaScript events bound to an element with a single new event

Assuming that there are a large number of elements throughout the site that have an unknown number and type of events bound to them.
If I need to override all of these events with one single bound event, and only that event will fire, what are some recommendations?
I would be binding the event to a click event handler, and I am using jQuery.
Thanks in advance.
You’re looking for jQuery#unbind.
To remove all event handlers on an element or a set of elements, just do:
$('.some-selector').unbind();
To unbind only click handlers, use unbind('click'):
$('.some-selector').unbind('click');
To unbind all click handlers and immediately bind your own handler after that, you can do something like this:
$('.some-selector').unbind('click').click(function(event) {
// Your code goes here
});
Note that this will only work for events bound using jQuery (using .bind or any jQuery method that uses .bind internally). If you want to remove all possible onclick events from a given set of elements, you could use:
$('.some-selector')
.unbind('click') // takes care of jQuery-bound click events
.attr('onclick', '') // clears `onclick` attributes in the HTML
.each(function() { // reset `onclick` event handlers
this.onclick = null;
});
I would like to provide a thought without removing all events all together (just override them).
If your new one single bound event (we call it "click" here) is specific to the element it binds to, then I believe you can ignore any other events simply by stopPropagation() function. Like this
$("specific-selector").on("click", ".specific-class", function (e) {
e.stopPropagation()
// e.stopImmediatePropagation()
/* your code continues ... */
});
It will stop events bubbles up, so your other events won't fire. use stopImmediatePropagation() to prevent other events attached onto the same elements as "click" does.
For example, if "mouseleave" event is also bind to $("specific-selector .specific-class") element, it won't fire, too.
At last, all other events won't fire on this element but your new "click" element.
The unsolved question is, what if other events also use stopPropagation()? ... Then I think the one with best specification wins, so try to avoid complex, too many events is final suggestion.
You can see "Direct and delegated events" on jQuery site for more information.
Looks like this is pretty simple actually:
$('#foo').unbind('click');
$('#foo').bind('click', myNewFunction);
Thanks for your responses though.
Try to use live instead of bind. Then you can easily remove live binding with die from selector which is fast operation and set another live equally fast.
$('selection here').live('..', .....); // multiple invocations
$('selection here').die();
$('selection here').live('click',.....);
DOM is not touched at all. Event condition is evaluated on event occurrence.
But generally if you just want to swap handler functions why not to do it this way:
var ahandler = function(evt) { /* first implementation */ }
$('.selector').bind('click', function(evt) { ahandler(evt); });
//and then if you want to change handlers
ahandler = function(evt) { /* new implementation */ };
This gives absolutely no cost of any changes, rebinding etc.

clicking on div fires binding for $('body').click

I have a div, I want to set it so that when I click on something else, it would hide the div.
So I did
$('body').click(function(){
if(loginOpened)
{
$('#loginWindow').animate({
'width':'0px',
'height':'0px'
},"fast");
}
loginOpened=false;
});
However, even when I click in the div itself the event is fired, is there anyway to prevent this?
You can stop it using
e.stopPropagation(); if there is a click event bound to the <div /> tag.
See event.stopPropagation()
Prevents the event from bubbling up
the DOM tree, preventing any parent
handlers from being notified of the
event.
Otherwise you can check the target of the event inside the body click. Check whether event.target is the same as your div.
See event.target
Just check the event.target. If the element that triggered the event is your div do not execute the code.
$('body').click(function(evt){
evt = evt || window.event
if ($(evt.target) != $('#loginWindow')) {
if(loginOpened)
{
$('#loginWindow').animate({
'width':'0px',
'height':'0px'
},"fast");
}
loginOpened=false;
}
});
Yes, but of course Microsoft and the rest of the world came to different conclusions about how to do it. This site gives a good clear rundown of what's needed: http://www.quirksmode.org/js/events_order.html .
I don't use jQuery but the jQuery way appears to be event.stopImmediatePropagation(); as seen in this question: jQuery Multiple Event Handlers - How to Cancel? .
A couple of changes from John's code:
$('body').click(function(ev){
// jQuery means never having to say "window.event"!
// Also, code's cleaner and faster if you don't branch,
// and choose simple breaks over more complex ones
if(!loginOpened) return;
// Lastly, compare using the DOM element;
// jQuery objects never compare as the "same"*
if (ev.target == $('#loginWindow').get(0)) return;
$('#loginWindow').animate({
'width':'0px',
'height':'0px'
},"fast");
loginOpened=false;
});
If trapping it in the body event doesn't work for you, you can just add a simple event handler to the div:
$('#loginWindow').click(function (ev) { ev.stopPropagation(); });
I was going to say return false, but that would prevent other things from firing off the div. stopPropagation just keeps the event from bubbling outward.
I could be really picky, of course...
//Delegation via the document element permits you to bind the event before
// the DOM is complete; no flashes of unbehaviored content
$(document).delegate('body', 'click', function(ev){
//You only have one instance of an id per page, right?
if(!loginOpened || ev.target.id == 'loginWindow') return;
//quotes and px? not necessary. This isn't json, and jQ's smart
$('#loginWindow').animate({width:0,height:0},"fast");
loginOpened=false;
});
* Don't believe me? Try:
jQuery('#notify-container') == jQuery('#notify-container')
Then try
jQuery('#notify-container').get(0) == jQuery('#notify-container').get(0)

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