Develop Reference

Right way to prevent additional events [duplicate]

They seem to be doing the same thing...
Is one modern and one old? Or are they supported by different browsers?
When I handle events myself (without framework) I just always check for both and execute both if present. (I also return false, but I have the feeling that doesn't work with events attached with node.addEventListener).
So why both? Should I keep checking for both? Or is there actually a difference?
(I know, a lot of questions, but they're all sort of the same =))

stopPropagation prevents further propagation of the current event in the capturing and bubbling phases.
preventDefault prevents the default action the browser makes on that event.
Examples
preventDefault
$("#but").click(function (event) {
event.preventDefault()
})
$("#foo").click(function () {
alert("parent click event fired!")
})
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="foo">
<button id="but">button</button>
</div>
stopPropagation
$("#but").click(function (event) {
event.stopPropagation()
})
$("#foo").click(function () {
alert("parent click event fired!")
})
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="foo">
<button id="but">button</button>
</div>
With stopPropagation, only the button's click handler is called while the div's click handler never fires.
Where as if you use preventDefault, only the browser's default action is stopped but the div's click handler still fires.
Below are some docs on the DOM event properties and methods from MDN:
event.cancelBubble
event.preventDefault()
event.returnValue
event.stopPropagation()
For IE9 and FF you can just use preventDefault & stopPropagation.
To support IE8 and lower replace stopPropagation with cancelBubble and replace preventDefault with returnValue

Terminology
From quirksmode.org:
Event capturing
When you use event capturing
| |
---------------| |-----------------
| element1 | | |
| -----------| |----------- |
| |element2 \ / | |
| ------------------------- |
| Event CAPTURING |
-----------------------------------
the event handler of element1 fires first, the event handler of element2 fires last.
Event bubbling
When you use event bubbling
/ \
---------------| |-----------------
| element1 | | |
| -----------| |----------- |
| |element2 | | | |
| ------------------------- |
| Event BUBBLING |
-----------------------------------
the event handler of element2 fires first, the event handler of element1 fires last.
Any event taking place in the W3C event model is first captured until it reaches the target element and then bubbles up again.
| | / \
-----------------| |--| |-----------------
| element1 | | | | |
| -------------| |--| |----------- |
| |element2 \ / | | | |
| -------------------------------- |
| W3C event model |
------------------------------------------
Interface
From w3.org, for event capture:
If the capturing EventListener wishes to prevent further processing of
the event from occurring it may call the stopPropagation method of the
Event interface. This will prevent further dispatch of the event,
although additional EventListeners registered at the same hierarchy
level will still receive the event. Once an event's stopPropagation
method has been called, further calls to that method have no
additional effect. If no additional capturers exist and
stopPropagation has not been called, the event triggers the
appropriate EventListeners on the target itself.
For event bubbling:
Any event handler may choose to prevent further event propagation by
calling the stopPropagation method of the Event interface. If any
EventListener calls this method, all additional EventListeners on the
current EventTarget will be triggered but bubbling will cease at that
level. Only one call to stopPropagation is required to prevent further
bubbling.
For event cancelation:
Cancelation is accomplished by calling the Event's preventDefault
method. If one or more EventListeners call preventDefault during
any phase of event flow the default action will be canceled.
Examples
In the following examples, a click on the hyperlink in the web browser triggers the event's flow (the event listeners are executed) and the event target's default action (a new tab is opened).
HTML:
<div id="a">
<a id="b" href="http://www.google.com/" target="_blank">Google</a>
</div>
<p id="c"></p>
JavaScript:
var el = document.getElementById("c");
function capturingOnClick1(ev) {
el.innerHTML += "DIV event capture<br>";
}
function capturingOnClick2(ev) {
el.innerHTML += "A event capture<br>";
}
function bubblingOnClick1(ev) {
el.innerHTML += "DIV event bubbling<br>";
}
function bubblingOnClick2(ev) {
el.innerHTML += "A event bubbling<br>";
}
// The 3rd parameter useCapture makes the event listener capturing (false by default)
document.getElementById("a").addEventListener("click", capturingOnClick1, true);
document.getElementById("b").addEventListener("click", capturingOnClick2, true);
document.getElementById("a").addEventListener("click", bubblingOnClick1, false);
document.getElementById("b").addEventListener("click", bubblingOnClick2, false);
Example 1: it results in the output
DIV event capture
A event capture
A event bubbling
DIV event bubbling
Example 2: adding stopPropagation() to the function
function capturingOnClick1(ev) {
el.innerHTML += "DIV event capture<br>";
ev.stopPropagation();
}
results in the output
DIV event capture
The event listener prevented further downward and upward propagation of the event. However it did not prevent the default action (a new tab opening).
Example 3: adding stopPropagation() to the function
function capturingOnClick2(ev) {
el.innerHTML += "A event capture<br>";
ev.stopPropagation();
}
or the function
function bubblingOnClick2(ev) {
el.innerHTML += "A event bubbling<br>";
ev.stopPropagation();
}
results in the output
DIV event capture
A event capture
A event bubbling
This is because both event listeners are registered on the same event target. The event listeners prevented further upward propagation of the event. However they did not prevent the default action (a new tab opening).
Example 4: adding preventDefault() to any function, for instance
function capturingOnClick1(ev) {
el.innerHTML += "DIV event capture<br>";
ev.preventDefault();
}
prevents a new tab from opening.

return false;
return false; does 3 separate things when you call it:
event.preventDefault() – It stops the browsers default behaviour.
event.stopPropagation() – It prevents the event from propagating (or “bubbling up”) the DOM.
Stops callback execution and returns immediately when called.
Note that this behaviour differs from normal (non-jQuery) event handlers, in which, notably, return false does not stop the event from bubbling up.
preventDefault();
preventDefault(); does one thing: It stops the browsers default behaviour.
When to use them?
We know what they do but when to use them? Simply it depends on what you want to accomplish. Use preventDefault(); if you want to “just” prevent the default browser behaviour. Use return false; when you want to prevent the default browser behaviour and prevent the event from propagating the DOM. In most situations where you would use return false; what you really want is preventDefault().
Examples:
Let’s try to understand with examples:
We will see pure JAVASCRIPT example
Example 1:
<div onclick='executeParent()'>
<a href='https://stackoverflow.com' onclick='executeChild()'>Click here to visit stackoverflow.com</a>
</div>
<script>
function executeChild() {
alert('Link Clicked');
}
function executeParent() {
alert('div Clicked');
}
</script>
Run the above code you will see the hyperlink ‘Click here to visit
stackoverflow.com‘ now if you click on that link first you will get
the javascript alert Link Clicked Next you will get the javascript
alert div Clicked and immediately you will be redirected to
stackoverflow.com.
Example 2:
<div onclick='executeParent()'>
<a href='https://stackoverflow.com' onclick='executeChild()'>Click here to visit stackoverflow.com</a>
</div>
<script>
function executeChild() {
event.preventDefault();
event.currentTarget.innerHTML = 'Click event prevented'
alert('Link Clicked');
}
function executeParent() {
alert('div Clicked');
}
</script>
Run the above code you will see the hyperlink ‘Click here to visit
stackoverflow.com‘ now if you click on that link first you will get
the javascript alert Link Clicked Next you will get the javascript
alert div Clicked Next you will see the hyperlink ‘Click here to
visit stackoverflow.com‘ replaced by the text ‘Click event prevented‘
and you will not be redirected to stackoverflow.com. This is due > to event.preventDefault() method we used to prevent the default click
action to be triggered.
Example 3:
<div onclick='executeParent()'>
<a href='https://stackoverflow.com' onclick='executeChild()'>Click here to visit stackoverflow.com</a>
</div>
<script>
function executeChild() {
event.stopPropagation();
event.currentTarget.innerHTML = 'Click event prevented'
alert('Link Clicked');
}
function executeParent() {
alert('div Clicked');
}
</script>
This time if you click on Link the function executeParent() will not
be called and you will not get the javascript alert div Clicked
this time. This is due to us having prevented the propagation to the
parent div using event.stopPropagation() method. Next you will see the
hyperlink ‘Click here to visit stackoverflow.com‘ replaced by the text
‘Click event is going to be executed‘ and immediately you will be
redirected to stackoverflow.com. This is because we haven’t prevented
the default click action from triggering this time using
event.preventDefault() method.
Example 4:
<div onclick='executeParent()'>
<a href='https://stackoverflow.com' onclick='executeChild()'>Click here to visit stackoverflow.com</a>
</div>
<script>
function executeChild() {
event.preventDefault();
event.stopPropagation();
event.currentTarget.innerHTML = 'Click event prevented'
alert('Link Clicked');
}
function executeParent() {
alert('Div Clicked');
}
</script>
If you click on the Link, the function executeParent() will not be
called and you will not get the javascript alert. This is due to us
having prevented the propagation to the parent div using
event.stopPropagation() method. Next you will see the hyperlink ‘Click
here to visit stackoverflow.com‘ replaced by the text ‘Click event
prevented‘ and you will not be redirected to stackoverflow.com. This
is because we have prevented the default click action from triggering
this time using event.preventDefault() method.
Example 5:
For return false I have three examples and all appear to be doing the exact same thing (just returning false), but in reality the
results are quite different. Here's what actually happens in each of
the above.
cases:
Returning false from an inline event handler prevents the browser from navigating to the link address, but it doesn't stop the event from propagating through the DOM.
Returning false from a jQuery event handler prevents the browser from navigating to the link address and it stops the event from propagating through the DOM.
Returning false from a regular DOM event handler does absolutely nothing.
Will see all three example.
Inline return false.
<div onclick='executeParent()'>
<a href='https://stackoverflow.com' onclick='return false'>Click here to visit stackoverflow.com</a>
</div>
<script>
var link = document.querySelector('a');
link.addEventListener('click', function() {
event.currentTarget.innerHTML = 'Click event prevented using inline html'
alert('Link Clicked');
});
function executeParent() {
alert('Div Clicked');
}
</script>
Returning false from a jQuery event handler.
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div>
<a href='https://stackoverflow.com'>Click here to visit stackoverflow.com</a>
</div>
<script>
$('a').click(function(event) {
alert('Link Clicked');
$('a').text('Click event prevented using return FALSE');
$('a').contents().unwrap();
return false;
});
$('div').click(function(event) {
alert('Div clicked');
});
</script>
Returning false from a regular DOM event handler.
<div onclick='executeParent()'>
<a href='https://stackoverflow.com' onclick='executeChild()'>Click here to visit stackoverflow.com</a>
</div>
<script>
function executeChild() {
event.currentTarget.innerHTML = 'Click event prevented'
alert('Link Clicked');
return false
}
function executeParent() {
alert('Div Clicked');
}
</script>
Hope these examples are clear. Try executing all these examples in a html file to see how they work.

This is the quote from here
Event.preventDefault
The preventDefault method prevents an event from carrying out its default functionality. For example, you would use preventDefault on an A element to stop clicking that element from leaving the current page:
//clicking the link will *not* allow the user to leave the page
myChildElement.onclick = function(e) {
e.preventDefault();
console.log('brick me!');
};
//clicking the parent node will run the following console statement because event propagation occurs
logo.parentNode.onclick = function(e) {
console.log('you bricked my child!');
};
While the element's default functionality is bricked, the event continues to bubble up the DOM.
Event.stopPropagation
The second method, stopPropagation, allows the event's default functionality to happen but prevents the event from propagating:
//clicking the element will allow the default action to occur but propagation will be stopped...
myChildElement.onclick = function(e) {
e.stopPropagation();
console.log('prop stop! no bubbles!');
};
//since propagation was stopped by the child element's onClick, this message will never be seen!
myChildElement.parentNode.onclick = function(e) {
console.log('you will never see this message!');
};
stopPropagation effectively stops parent elements from knowing about a given event on its child.
While a simple stop method allows us to quickly handle events, it's
important to think about what exactly you want to happen with
bubbling. I'd bet that all a developer really wants is preventDefault
90% of the time! Incorrectly "stopping" an event could cause you
numerous troubles down the line; your plugins may not work and your
third party plugins could be bricked. Or worse yet -- your code
breaks other functionality on a site.

event.preventDefault()
Prevents the browsers default behaviour (such as opening a link), but does not stop the event from bubbling up the DOM.
event.stopPropagation()Prevents the event from bubbling up the DOM, but does not stop the browsers default behaviour.
return false;Usually seen in jQuery code, it Prevents the browsers default behaviour, Prevents the event from bubbling up the
DOM, and immediately Returns from any callback.
Check out this really nice & easy 4 min read with examples from where the above piece was taken.

event.preventDefault(); Stops the default action of an element from happening.
event.stopPropagation(); Prevents the event from bubbling up the DOM tree, preventing any parent handlers from being notified of the event.
For example, if there is a link with a click method attached inside of a DIV or FORM that also has a click method attached, it will prevent the DIV or FORM click method from firing.

Event.preventDefault- stops browser default behaviour. Now comes what is browser default behaviour. Assume you have a anchor tag and it has got a href attribute and this anchor tag is nested inside a div tag which has got a click event. Default behaviour of anchor tag is when clicked on the anchor tag it should navigate, but what event.preventDefault does is it stops the navigation in this case. But it never stops the bubbling of event or escalation of event i.e
<div class="container">
Click Me!
</div>
$('.container').on('click', function(e) {
console.log('container was clicked');
});
$('.element').on('click', function(e) {
e.preventDefault(); // Now link won't go anywhere
console.log('element was clicked');
});
The result will be
"element was clicked"
"container was clicked"
Now event.StopPropation it stops bubbling of event or escalation of event. Now with above example
$('.container').on('click', function(e) {
console.log('container was clicked');
});
$('.element').on('click', function(e) {
e.preventDefault(); // Now link won't go anywhere
e.stopPropagation(); // Now the event won't bubble up
console.log('element was clicked');
});
Result will be
"element was clicked"
For more info refer this link
https://codeplanet.io/preventdefault-vs-stoppropagation-vs-stopimmediatepropagation/

$("#but").click(function(event){
console.log("hello");
event.preventDefault();
});
$("#foo").click(function(){
alert("parent click event fired !");
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="foo">
<button id="but">button</button>
</div>

e.stopPropogation() Equivalent for Capture Phase of Click Event?

I'm looking for a way in JS to stop a click event from continuing down the DOM to a nested child element (capture phase) when the parent element was clicked.
It would be the inverse of the e.stopPropogation() function to prevent a click event from bubbling up.
Is there a native JS function for this?
Edit 03/10
Link to example
Edit 03/11
Typo in the function call - it's stopPropagation(), not stopPropogation(). Thanks to #JackPattishall for the find.

yes there is native js function for capturing event in capture phase.
In all browsers, except IE<9, there are two stages of event processing.
The event first goes down - that’s called capturing, and then bubbles up. This behavior is standartized in W3C specification.
All methods of event handling ignore the caputiring phase. Using addEventListener with last argument true is only the way to catch the event at capturing.
elem.addEventListener( type, handler, phase )
phase = true
The handler is set on the capturing phase.
phase = false
The handler is set on the bubbling phase.
For better understanding of event capturing and bubbling you can follow this link

okey, One thing you and do is use the stopPropogation() at the top in Dom.
eg. you have a table(#table1) and elements(tr,td).
so, if i do:
table1.addEventListener("click",function(event){
event.stopPropagation();
console.log(this);
},true);
tableElem[2].addEventListener("click",function(event){
console.log(this);
});
tableElem[2].addEventListener("click",function(event){
console.log("hii");
});
The event will be intercepted at top and propogation will be stopped.
stopPropogation() stops propagation irrespective of on which step event is intercepted.

How to add an eventhandler which can prevent any other click eventhandler with jQuery?

I would like to implement a confirmation logic for links or buttons, where I can annotate the related element with a special data-confirm attribute. If this attribute exists on the element, I would like to attach a click handler which has the power to prevent any other handler including default event, and other jQuery handlers added before or after my confirm handler was added.
Here is my code:
$(document).on("click", "a[data-confirm], button[data-confirm]", function(e) {
var confirmData = $(this).data("confirm");
if (confirmData === "true")
confirmData = $(this).prop("title");
if (confirmData && !confirm(confirmData)) {
e.stopImmediatePropagation();
e.stopPropagation();
e.preventDefault();
return false;
}
return true;
});
The problem is that I'm not sure about where this handler will go into the handlers list, so I guess there is a good probability that other handlers could execute before it. Also, I'm not sure if this handler will precede for example knockoutjs' click binding.

To prevent other handlers from being called use stopImmediatePropagation() and to prevent default behavior use preventDefault().
Like so:
$("body").on("click", ".elementClass[attributeName]", function(event){
event.stopImmediatePropagation();
event.preventDefault();
});
By adding the [attributeName] in the selector, the selector will only apply to elements with the attribute "attributeName"
In the example above this will be executed before your $(document) handler as the event bubbles up the DOM and gets to the body before it gets to the document. To ensure that this event is attached sooner, you can attach the handler to the element like so:
$(".elementClass[attributeName]").on("click", function(event){
event.stopImmediatePropagation();
event.preventDefault();
});
The downside to this, is that this handler must be attached after the element has the attribute.
Another technique you can use with just vanilla JavaScript, however, is event capturing: https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener.
If true, useCapture indicates that the user wishes to initiate capture. After initiating capture, all events of the specified type will be dispatched to the registered listener before being dispatched to any EventTarget beneath it in the DOM tree. Events which are bubbling upward through the tree will not trigger a listener designated to use capture
You can do something like this:
document.addEventListener("click", function(event){
if(event.target.hasAttribute("attributeName")){ // jQuery: if($(event.target).attr("attributeName")){...
event.stopPropagation();
event.preventDefault();
//Do stuff
}
}, true);
By adding true at the end the event is captured, meaning this will be run before other handlers.

If an element has more than one click handlers, the execution order of those is unspecified. So you can't reliably make one always execute first.
Although all EventListeners on the EventTarget are guaranteed to be triggered by any event which is received by that EventTarget, no specification is made as to the order in which they will receive the event with regards to the other EventListeners on the EventTarget.
W3C-Events-flow-basics

Why is the event listener for the invalid event not being called when using event bubbling?

When I try add an event listener to the invalid event of the document it is not called when I use the default event bubbling like this.
document.addEventListener("invalid", function (e) {
console.log(e.target);
}, false);
When I set the last parameter to true the event listener is called like expected. Thanks to What is event bubbling and capturing? I think I understand the difference between event capturing and bubbling, but I don't understand how this applies to my case. Why is it making a difference here?

According to the MDN reference, which is usually accurate and which appears to match reality in this case, invalid events do not bubble. They fire only on the input and the form.

jQuery event bubbling

I want to understand how exactly to interpret bubbling. Does it mean going up the HTML code hierarchy or something else?
Secondly, I was going through an example and I could not understand the last part where it says
The P-based click handler listens for the click event and then prevents it from being propagated (bubbling up)
What does this mean?

The concept of "bubbling up" is like if you have a child element with a click event and you don't want it to trigger the click event of the parent. You could use event.stopPropagation().
event.stopPropagation() basically says only apply this click event to THIS CHILD NODE and don't tell the parent containers anything because I don't want them to react.
Event Capturing:
| |
---------------| |-----------------
| element1 | | |
| -----------| |----------- |
| |element2 \ / | |
| ------------------------- |
| Event CAPTURING |
-----------------------------------
Event Bubbling:
/ \
---------------| |-----------------
| element1 | | |
| -----------| |----------- |
| |element2 | | | |
| ------------------------- |
| Event BUBBLING |
-----------------------------------
If you are using live() or delegate() you will need to return false;, though it may not work. Read the quote below.
Per jQuery docs:
Since the .live() method handles events once they have propagated to
the top of the document, it is not possible to stop propagation of
live events. Similarly, events handled by .delegate() will propagate
to the elements to which they are delegated; event handlers bound on
any elements below it in the DOM tree will already have been executed
by the time the delegated event handler is called. These handlers,
therefore, may prevent the delegated handler from triggering by
calling event.stopPropagation() or returning false.
In the past it was a platform issue, Internet Explorer had a bubbling model, and Netscape was more about capturing (yet supported both).
The W3C model calls for you be able to choose which one you want.
I think bubbling is more popular because, as stated there are some platforms that only support bubbling...and it sort of makes sense as a "default" mode.
Which one you choose is largely a product of what you are doing and what makes sense to you.
More info http://www.quirksmode.org/js/events_order.html
Another great resource: http://fuelyourcoding.com/jquery-events-stop-misusing-return-false/

return false;
will prevent "bubbling". It's used to stop default actions like checking a checkbox, opening a select, a click, etc.
To stop further handlers from executing after one bound using .live(),
the handler must return false. Calling .stopPropagation() will not
accomplish this.
From Caveats in jQuery .live()
Reasoning (thanks to #AlienWebguy):
The reason stopPropagation() doesn't work with live() is that live() binds the event to document so by the time it fires there's no where else for it to propagate.

What it says is that the live () method attach a handler to the document element and check the target of the event to see where it comes from. If the target match the selector, then it fires the eventHandler. All that repose on the bubbling event system.
In the example, the click handler on the p element, witch is an ancestor of the a element, cancel the bubbling by returning false. Then the document element will never receive the event, so it will not trigger the event handler.

In the below example it is attaching a click event to anchor with id "anchor". This anchor is within a div which also has a click event attached. If we click on this anchor it is as good as we are clicking on the containing div. Now if we want to do some stuff on this anchor click but do not want the div's click to be fired we can stop the event bubling as below.
<div id="div">
</div>
$("#div").click(function(e){//On anchor click this event will not be fired as we have stop the event propagation in anchor click handler.
//Do stuff here
});
$("#anchor").click(function(e){
//Do stuff here
//This line stops the event bubling and
//jquery has abstracted it in the event object to make it cross browser compatible.
e.stopPropagation();
});

Also:
event.stopPropagation()
http://api.jquery.com/event.stopPropagation/

Yes, the event goes up the tree and if any element has a handler for that event it will be called.
By adding return:false in a handler of one of the elements the event will be prevented from bubbling.

These two links provide clear and elaborate explanation on event bubbling (as well as commonly used event concepts).
http://jqfundamentals.com/chapter/events
http://www.mattlunn.me.uk/blog/2012/05/what-does-event-bubbling-mean/
From the first link
event will be triggered for the a element as well as for all of
the elements that contain the a — all the way up to the document
From the second link
<div>
<h1>
<a href="#">
<span>Hello</span>
</a>
</h1>
</div>
Lets assume we click the span, which causes a click event to be fired on the span; nothing revolutionary so far. However, the event then propagates (or bubbles) to the parent of the span (the ), and a click event is fired on that. This process repeats for the next parent (or ancestor) up to the document element.
Now let's put all this into the context of a DOM. The DOM is a... tree and each element is a node in the DOM tree. Bubbling is then merely the traversal of a node, some element to the root node, document (follow your parent until you can't anymore)