Jquery events, simple clicks, how and why?

Jquery events, simple clicks, how and why? - javascript

So i have some data on a page (a table) which based on some options elsewhere may get ajax reloaded from the server.
This table has buttons in it that can be clicked to make other things happen to the records in the table.
I notice that this ...
http://api.jquery.com/on/
... is the recommended approach for attaching simple event handlers to elements but that only attaches to elements that exist right now, and when I do my ajax load I lose the attached handlers.
So I started using this ... http://api.jquery.com/live/ ... and guess what, jquery team did their usual and deprecated it saying I should be using "on".
These functions behave very differently yet jquery docs say i should be using them interchangably so ...
Can someone explain the "on" equivelent of this and how I can get it to work with elements after an ajax call replacing the elements that hae previously been attached to ...
$("some selector").live('click', function (e) {
// some code code
e.preventDefault();
return false;
});
My understanding is that you would do something like ...
$("some selector").on('click', function (e) {
// some code code
e.preventDefault();
return false;
});
My guess is that I then have to re-run this code after performing my ajax call by putting this in to some sort of "initClicks" function and calling it both on page load and after the ajax call.
This seems to be a bit of a back step to me ... or have i missed something here?

Since the elements are added dynamically, you need to use event delegation to register the event handler
// New way (jQuery 1.7+) - .on(events, selector, handler)
$(document).on('click', 'some selector', function(event) {
// some code code
e.preventDefault();
return false;
});
Also, either use e.preventDefault() or return false, as:
return false = e.preventDefault() + e.stopPropagation()
So, there is no need to use both of them at same time.

When you use .on('click', function (e) {}) function, it works only for existing elements.
To handle click event on all selector elements, even for elements which will be added in future, you can use one of these functions:
$(document).on('click', "some selector", function (e) {
// some code code
e.preventDefault();
return false;
});
or:
$("body").delegate("a", "click", function () {
// your code goes here
});
For more information read article about Understanding Event Delegation

live() is not magic, it cannot see future elements, what it was doing is to attach a listener to the first root element of your page document and checks every bubbled event if it match your target selector, and when it find a match, it executes your function.
this is called event delegation
live() has been deprecated for good reasons, mainly the performance hit caused by using it.
then the jQUery team introduced the delegate() function which gave us a new way to achieve the exact result, but it has addressed the performance hit very cleverly by limiting the scope in which it will listen to bubbled events to the possible nearest parent of your now & future elements.
when they introduced the On() function, they gave you the ability to use it as normal event handler, or as a delegated handler for future elements.
so I believe they did a good job for this, giving us the flexibility to use it as we wish according to the specific scenario.
Code Examples:
using delegate():
$( "#TAGERT_ID" ).delegate( "a", "click", function() { // your code goes here}
using on() (for delegated events)
$( "#TAGERT_ID" ).on( "click", "a", function() { // your code goes here}
both ways are the same, and will handle future clicks on a which will be added in the future inside your TARGET_ID element.
TARGET_ID is an example for using ID for your selector, but you can use whatever selector according to your specific need.

The equivalent of said live is
$(document).on('click', "some selector", function (e) {
// some code code
e.preventDefault();
return false;
});
The on() is a single stop for all event handler formats, the model you used is the same as
$("some selector").click(function (e) {
// some code code
e.preventDefault();
return false;
});
which does work based event delegation.

You can never actually attach event listener to an element which does not exist in DOM yet. What live and on method do is attach listener on a parent which exists right now. live is nothing but an on attached on document itself.

Related

preventing an inline script from running [duplicate]

I have an input type="image". This acts like the cell notes in Microsoft Excel. If someone enters a number into the text box that this input-image is paired with, I setup an event handler for the input-image. Then when the user clicks the image, they get a little popup to add some notes to the data.
My problem is that when a user enters a zero into the text box, I need to disable the input-image's event handler. I have tried the following, but to no avail.
$('#myimage').click(function { return false; });

jQuery ≥ 1.7
With jQuery 1.7 onward the event API has been updated, .bind()/.unbind() are still available for backwards compatibility, but the preferred method is using the on()/off() functions. The below would now be,
$('#myimage').click(function() { return false; }); // Adds another click event
$('#myimage').off('click');
$('#myimage').on('click.mynamespace', function() { /* Do stuff */ });
$('#myimage').off('click.mynamespace');
jQuery < 1.7
In your example code you are simply adding another click event to the image, not overriding the previous one:
$('#myimage').click(function() { return false; }); // Adds another click event
Both click events will then get fired.
As people have said you can use unbind to remove all click events:
$('#myimage').unbind('click');
If you want to add a single event and then remove it (without removing any others that might have been added) then you can use event namespacing:
$('#myimage').bind('click.mynamespace', function() { /* Do stuff */ });
and to remove just your event:
$('#myimage').unbind('click.mynamespace');

This wasn't available when this question was answered, but you can also use the live() method to enable/disable events.
$('#myimage:not(.disabled)').live('click', myclickevent);
$('#mydisablebutton').click( function () { $('#myimage').addClass('disabled'); });
What will happen with this code is that when you click #mydisablebutton, it will add the class disabled to the #myimage element. This will make it so that the selector no longer matches the element and the event will not be fired until the 'disabled' class is removed making the .live() selector valid again.
This has other benefits by adding styling based on that class as well.

This can be done by using the unbind function.
$('#myimage').unbind('click');
You can add multiple event handlers to the same object and event in jquery. This means adding a new one doesn't replace the old ones.
There are several strategies for changing event handlers, such as event namespaces. There are some pages about this in the online docs.
Look at this question (that's how I learned of unbind). There is some useful description of these strategies in the answers.
How to read bound hover callback functions in jquery

If you want to respond to an event just one time, the following syntax should be really helpful:
$('.myLink').bind('click', function() {
//do some things
$(this).unbind('click', arguments.callee); //unbind *just this handler*
});
Using arguments.callee, we can ensure that the one specific anonymous-function handler is removed, and thus, have a single time handler for a given event. Hope this helps others.

maybe the unbind method will work for you
$("#myimage").unbind("click");

I had to set the event to null using the prop and the attr. I couldn't do it with one or the other. I also could not get .unbind to work. I am working on a TD element.
.prop("onclick", null).attr("onclick", null)

If event is attached this way, and the target is to be unattached:
$('#container').on('click','span',function(eo){
alert(1);
$(this).off(); //seams easy, but does not work
$('#container').off('click','span'); //clears click event for every span
$(this).on("click",function(){return false;}); //this works.
});

You may be adding the onclick handler as inline markup:
<input id="addreport" type="button" value="Add New Report" onclick="openAdd()" />
If so, the jquery .off() or .unbind() won't work. You need to add the original event handler in jquery as well:
$("#addreport").on("click", "", function (e) {
openAdd();
});
Then the jquery has a reference to the event handler and can remove it:
$("#addreport").off("click")
VoidKing mentions this a little more obliquely in a comment above.

If you use $(document).on() to add a listener to a dynamically created element then you may have to use the following to remove it:
// add the listener
$(document).on('click','.element',function(){
// stuff
});
// remove the listener
$(document).off("click", ".element");

To remove ALL event-handlers, this is what worked for me:
To remove all event handlers mean to have the plain HTML structure without all the event handlers attached to the element and its child nodes. To do this, jQuery's clone() helped.
var original, clone;
// element with id my-div and its child nodes have some event-handlers
original = $('#my-div');
clone = original.clone();
//
original.replaceWith(clone);
With this, we'll have the clone in place of the original with no event-handlers on it.
Good Luck...

Updated for 2014
Using the latest version of jQuery, you're now able to unbind all events on a namespace by simply doing $( "#foo" ).off( ".myNamespace" );

Best way to remove inline onclick event is $(element).prop('onclick', null);

Thanks for the information. very helpful i used it for locking page interaction while in edit mode by another user. I used it in conjunction with ajaxComplete. Not necesarily the same behavior but somewhat similar.
function userPageLock(){
$("body").bind("ajaxComplete.lockpage", function(){
$("body").unbind("ajaxComplete.lockpage");
executePageLock();
});
};
function executePageLock(){
//do something
}

In case .on() method was previously used with particular selector, like in the following example:
$('body').on('click', '.dynamicTarget', function () {
// Code goes here
});
Both unbind() and .off() methods are not going to work.
However, .undelegate() method could be used to completely remove handler from the event for all elements which match the current selector:
$("body").undelegate(".dynamicTarget", "click")

I know this comes in late, but why not use plain JS to remove the event?
var myElement = document.getElementById("your_ID");
myElement.onclick = null;
or, if you use a named function as an event handler:
function eh(event){...}
var myElement = document.getElementById("your_ID");
myElement.addEventListener("click",eh); // add event handler
myElement.removeEventListener("click",eh); //remove it

This also works fine .Simple and easy.see http://jsfiddle.net/uZc8w/570/
$('#myimage').removeAttr("click");

if you set the onclick via html you need to removeAttr ($(this).removeAttr('onclick'))
if you set it via jquery (as the after the first click in my examples above) then you need to unbind($(this).unbind('click'))

All the approaches described did not work for me because I was adding the click event with on() to the document where the element was created at run-time:
$(document).on("click", ".button", function() {
doSomething();
});
My workaround:
As I could not unbind the ".button" class I just assigned another class to the button that had the same CSS styles. By doing so the live/on-event-handler ignored the click finally:
// prevent another click on the button by assigning another class
$(".button").attr("class","buttonOff");
Hope that helps.

Hope my below code explains all.
HTML:
(function($){
$("#btn_add").on("click",function(){
$("#btn_click").on("click",added_handler);
alert("Added new handler to button 1");
});
$("#btn_remove").on("click",function(){
$("#btn_click").off("click",added_handler);
alert("Removed new handler to button 1");
});
function fixed_handler(){
alert("Fixed handler");
}
function added_handler(){
alert("new handler");
}
$("#btn_click").on("click",fixed_handler);
$("#btn_fixed").on("click",fixed_handler);
})(jQuery);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<button id="btn_click">Button 1</button>
<button id="btn_add">Add Handler</button>
<button id="btn_remove">Remove Handler</button>
<button id="btn_fixed">Fixed Handler</button>

I had an interesting case relevant to this come up at work today where there was a scroll event handler for $(window).
// TO ELIMINATE THE RE-SELECTION AND
// RE-CREATION OF THE SAME OBJECT REDUNDANTLY IN THE FOLLOWING SNIPPETS
let $window = $(window);
$window.on('scroll', function() { .... });
But, to revoke that event handler, we can't just use
$window.off('scroll');
because there are likely other scroll event handlers on this very common target, and I'm not interested in hosing that other functionality (known or unknown) by turning off all of the scroll handlers.
My solution was to first abstract the handler functionality into a named function, and use that in the event listener setup.
function handleScrollingForXYZ() { ...... }
$window.on('scroll', handleScrollingForXYZ);
And then, conditionally, when we need to revoke that, I did this:
$window.off('scroll', $window, handleScrollingForXYZ);
The janky part is the 2nd parameter, which is redundantly selecting the original selector. But, the jquery documentation for .off() only provides one method signature for specifying the handler to remove, which requires this middle parameter to be
A selector which should match the one originally passed to .on() when attaching event handlers.
I haven't ventured to test it out with a null or '' as the 2nd parameter, but perhaps the redundant $window isn't necessary.

How to unbind from click event? [duplicate]

I have an input type="image". This acts like the cell notes in Microsoft Excel. If someone enters a number into the text box that this input-image is paired with, I setup an event handler for the input-image. Then when the user clicks the image, they get a little popup to add some notes to the data.
My problem is that when a user enters a zero into the text box, I need to disable the input-image's event handler. I have tried the following, but to no avail.
$('#myimage').click(function { return false; });

jQuery ≥ 1.7
With jQuery 1.7 onward the event API has been updated, .bind()/.unbind() are still available for backwards compatibility, but the preferred method is using the on()/off() functions. The below would now be,
$('#myimage').click(function() { return false; }); // Adds another click event
$('#myimage').off('click');
$('#myimage').on('click.mynamespace', function() { /* Do stuff */ });
$('#myimage').off('click.mynamespace');
jQuery < 1.7
In your example code you are simply adding another click event to the image, not overriding the previous one:
$('#myimage').click(function() { return false; }); // Adds another click event
Both click events will then get fired.
As people have said you can use unbind to remove all click events:
$('#myimage').unbind('click');
If you want to add a single event and then remove it (without removing any others that might have been added) then you can use event namespacing:
$('#myimage').bind('click.mynamespace', function() { /* Do stuff */ });
and to remove just your event:
$('#myimage').unbind('click.mynamespace');

This wasn't available when this question was answered, but you can also use the live() method to enable/disable events.
$('#myimage:not(.disabled)').live('click', myclickevent);
$('#mydisablebutton').click( function () { $('#myimage').addClass('disabled'); });
What will happen with this code is that when you click #mydisablebutton, it will add the class disabled to the #myimage element. This will make it so that the selector no longer matches the element and the event will not be fired until the 'disabled' class is removed making the .live() selector valid again.
This has other benefits by adding styling based on that class as well.

This can be done by using the unbind function.
$('#myimage').unbind('click');
You can add multiple event handlers to the same object and event in jquery. This means adding a new one doesn't replace the old ones.
There are several strategies for changing event handlers, such as event namespaces. There are some pages about this in the online docs.
Look at this question (that's how I learned of unbind). There is some useful description of these strategies in the answers.
How to read bound hover callback functions in jquery

If you want to respond to an event just one time, the following syntax should be really helpful:
$('.myLink').bind('click', function() {
//do some things
$(this).unbind('click', arguments.callee); //unbind *just this handler*
});
Using arguments.callee, we can ensure that the one specific anonymous-function handler is removed, and thus, have a single time handler for a given event. Hope this helps others.

maybe the unbind method will work for you
$("#myimage").unbind("click");

I had to set the event to null using the prop and the attr. I couldn't do it with one or the other. I also could not get .unbind to work. I am working on a TD element.
.prop("onclick", null).attr("onclick", null)

If event is attached this way, and the target is to be unattached:
$('#container').on('click','span',function(eo){
alert(1);
$(this).off(); //seams easy, but does not work
$('#container').off('click','span'); //clears click event for every span
$(this).on("click",function(){return false;}); //this works.
});

You may be adding the onclick handler as inline markup:
<input id="addreport" type="button" value="Add New Report" onclick="openAdd()" />
If so, the jquery .off() or .unbind() won't work. You need to add the original event handler in jquery as well:
$("#addreport").on("click", "", function (e) {
openAdd();
});
Then the jquery has a reference to the event handler and can remove it:
$("#addreport").off("click")
VoidKing mentions this a little more obliquely in a comment above.

If you use $(document).on() to add a listener to a dynamically created element then you may have to use the following to remove it:
// add the listener
$(document).on('click','.element',function(){
// stuff
});
// remove the listener
$(document).off("click", ".element");

To remove ALL event-handlers, this is what worked for me:
To remove all event handlers mean to have the plain HTML structure without all the event handlers attached to the element and its child nodes. To do this, jQuery's clone() helped.
var original, clone;
// element with id my-div and its child nodes have some event-handlers
original = $('#my-div');
clone = original.clone();
//
original.replaceWith(clone);
With this, we'll have the clone in place of the original with no event-handlers on it.
Good Luck...

Updated for 2014
Using the latest version of jQuery, you're now able to unbind all events on a namespace by simply doing $( "#foo" ).off( ".myNamespace" );

Best way to remove inline onclick event is $(element).prop('onclick', null);

Thanks for the information. very helpful i used it for locking page interaction while in edit mode by another user. I used it in conjunction with ajaxComplete. Not necesarily the same behavior but somewhat similar.
function userPageLock(){
$("body").bind("ajaxComplete.lockpage", function(){
$("body").unbind("ajaxComplete.lockpage");
executePageLock();
});
};
function executePageLock(){
//do something
}

In case .on() method was previously used with particular selector, like in the following example:
$('body').on('click', '.dynamicTarget', function () {
// Code goes here
});
Both unbind() and .off() methods are not going to work.
However, .undelegate() method could be used to completely remove handler from the event for all elements which match the current selector:
$("body").undelegate(".dynamicTarget", "click")

I know this comes in late, but why not use plain JS to remove the event?
var myElement = document.getElementById("your_ID");
myElement.onclick = null;
or, if you use a named function as an event handler:
function eh(event){...}
var myElement = document.getElementById("your_ID");
myElement.addEventListener("click",eh); // add event handler
myElement.removeEventListener("click",eh); //remove it

This also works fine .Simple and easy.see http://jsfiddle.net/uZc8w/570/
$('#myimage').removeAttr("click");

if you set the onclick via html you need to removeAttr ($(this).removeAttr('onclick'))
if you set it via jquery (as the after the first click in my examples above) then you need to unbind($(this).unbind('click'))

All the approaches described did not work for me because I was adding the click event with on() to the document where the element was created at run-time:
$(document).on("click", ".button", function() {
doSomething();
});
My workaround:
As I could not unbind the ".button" class I just assigned another class to the button that had the same CSS styles. By doing so the live/on-event-handler ignored the click finally:
// prevent another click on the button by assigning another class
$(".button").attr("class","buttonOff");
Hope that helps.

Hope my below code explains all.
HTML:
(function($){
$("#btn_add").on("click",function(){
$("#btn_click").on("click",added_handler);
alert("Added new handler to button 1");
});
$("#btn_remove").on("click",function(){
$("#btn_click").off("click",added_handler);
alert("Removed new handler to button 1");
});
function fixed_handler(){
alert("Fixed handler");
}
function added_handler(){
alert("new handler");
}
$("#btn_click").on("click",fixed_handler);
$("#btn_fixed").on("click",fixed_handler);
})(jQuery);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<button id="btn_click">Button 1</button>
<button id="btn_add">Add Handler</button>
<button id="btn_remove">Remove Handler</button>
<button id="btn_fixed">Fixed Handler</button>

I had an interesting case relevant to this come up at work today where there was a scroll event handler for $(window).
// TO ELIMINATE THE RE-SELECTION AND
// RE-CREATION OF THE SAME OBJECT REDUNDANTLY IN THE FOLLOWING SNIPPETS
let $window = $(window);
$window.on('scroll', function() { .... });
But, to revoke that event handler, we can't just use
$window.off('scroll');
because there are likely other scroll event handlers on this very common target, and I'm not interested in hosing that other functionality (known or unknown) by turning off all of the scroll handlers.
My solution was to first abstract the handler functionality into a named function, and use that in the event listener setup.
function handleScrollingForXYZ() { ...... }
$window.on('scroll', handleScrollingForXYZ);
And then, conditionally, when we need to revoke that, I did this:
$window.off('scroll', $window, handleScrollingForXYZ);
The janky part is the 2nd parameter, which is redundantly selecting the original selector. But, the jquery documentation for .off() only provides one method signature for specifying the handler to remove, which requires this middle parameter to be
A selector which should match the one originally passed to .on() when attaching event handlers.
I haven't ventured to test it out with a null or '' as the 2nd parameter, but perhaps the redundant $window isn't necessary.

Prevent click event on the clicked element?

I have a click event on the body of my document:
$("body").on('click.findElem', function(e) {
e.stopPropagation();
e.preventDefault();
self.hinter(e.target);
return false;
});
It basically catches the clicked target and does something to it. However, there are some targets that already have a click event on them, and they prevent my click from being executed at all. How do I overcome that issue? I tried unbinding it, but the click doesn't even work at all to actually execute the unbinding.

e.stopImmediatePropagation() does the job, but only if your handler executes before whatever other handler exists.
Unfortunately there is no way to insert your own handler in the first position - but you can use this nasty hack if the other handlers were bound using jQuery, too: How do you force your javascript event to run first, regardless of the order in which the events were added?
If you really need this you might want to bind an event handler in capture mode using the native DOM API: https://developer.mozilla.org/en-US/docs/Web/API/EventTarget.addEventListener
Capture handlers are triggered before bubble handlers (which are used by jQuery and most other scripts) so that way you have very high chance to execute your handler first.

try this and see demo
$( "body" ).on( "click", ".clickme:not(.clicked)", function( event ) {
$(this).addClass('clicked');
alert('here');
});

i tend to not use on and stick with the bind/unbind combo.
i have some pages that reload partial content and then has to rebind the events.
i tipically do something like this
$(".theobjectsiwant").unbind("click").bind("click", function() {
alert('hi there');
});
If you want/have to stick with the on() function, you shouldn't mix on() with unbind() and try a similar approach with .off("click").on("click")
Check here for a sample http://api.jquery.com/off/

Proper use of .on method in Jquery

I really liked the .live method as it was straightforward and essentially not much different than your standard event handler.
Alas, it was deprecated and I'm left with the .on method.
Basically, I'm loading and dynamically loading content that I'll need the same event handler triggered on. Rather than add the event handler twice or however many times. .live was great for this, but .on has replaced it and I just can't seem to get it to work.
check this code:
jQuery('#who_me').live('click', function(){
alert('test123');
return false;
});
should be the same as:
jQuery('#who_me').on('click', function(){
alert('test123');
return false;
});
but when I replace content with the .html method after an ajax call only the live method works.
Can anyone clear this up for me?

You aren't using .on() correctly. This is a better implementation if the #who_me object comes and goes.
jQuery(document.body).on('click', '#who_me', function(){
alert('test123');
return false;
});
The selector you use in the jQuery object for .on() must be an object that is present at the time you install the event handler and never gets removed or recreated and is either the object you want the event installed on or a parent of that object. The selector passed as the 2nd argument to .on() is an optional selector that matches the object you want the event on. If you want .live() type behavior, then you must pass a static parent object in the jQuery object and a selector that matches the actual object you want the event on in the 2nd argument.
Ideally, you put a parent object in the jQuery object that is relatively close to the dynamic object. I've shown document.body just because I know that would work and don't know the rest of your HTML, but you'd rather put it closer to your actual object. If you put too many dynamic event handlers on the document object or on document.body, then event handling can really slow down, particularly if you have complicated selectors or handlers for frequent events like click or mousemove.
For reference, the 100% equivalent to your .live() code is this:
jQuery(document).on('click', '#who_me', function(){
alert('test123');
return false;
});
.live() just installs all its event handlers on the document object, and uses event bubbling to see all the events that happen on other objects in the page. jQuery has deprecated .live() because it's better to NOT install all your live event handlers on the document object (for performance reasons). So, pick a static parent object that is closer to your object.

The context when using .live was document, therefore the selector for .on should be document
$(document).on("click","#who_me",function(){...});

The way you're using on, it's basically a replacement for bind, rather than live. With on, as with live and delegate, you can use event delegation, but you must supply a specific containing element (as was always the case with delegate).
At the simplest level, this can be document. In this case, the handler will function exactly as live would have:
jQuery(document).on('click', '#who_me', function() {
alert('test123');
return false;
});
It would be better, however, to find the closest element to contain the elements that will exist. This gives performance gains.
jQuery('#some_el').on('click', '#who_me', function() {
alert('test123');
return false;
});

jQuery(document).on('click', '#who_me', function(){
alert('test123');
return false;
});
should be the equivalent of jQuery.live('#who_me', function() { // code here });

Nope.
$( '#who_me' ).live( 'click', function () { ... });
is the same as:
$( document ).on( 'click', '#who_me', function () { ... });
However, you usually don't want to bind to much handlers to the document object. Instead you bind to the nearest static ancestor (of #who_me, in this case). So:
$( '#wrapper' ).on( 'click', '#who_me', function () { ... });
where #wrapper is an ancestor of #who_me.

To replace .live() you need one more parameter int he .on() call.
// do not use! - .live(events, handler)
$('#container a').live('click', function(event) {
event.preventDefault();
console.log('item anchor clicked');
});
// new way (jQuery 1.7+) - .on(events, selector, handler)
$('#container').on('click', 'a', function(event) {
event.preventDefault();
console.log('item anchor clicked');
});
Source: http://www.andismith.com/blog/2011/11/on-and-off/

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.

Develop Reference

JavaScript is the programming language of the Web.

Jquery events, simple clicks, how and why? - javascript

You can never actually attach event listener to an element which does not exist in DOM yet. What live and on method do is attach listener on a parent which exists right now. live is nothing but an on attached on document itself.

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Prevent click event on the clicked element?

Proper use of .on method in Jquery

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

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