---
title: "Return false has changed in jquery 1.4.3"
description:
"The behavior of return false has changed in jQuery 1.4.3. This blog
discusses what changed."
canonical_url: "https://www.bigbinary.com/blog/return-false-in-jquery-1.4.3"
markdown_url: "https://www.bigbinary.com/blog/return-false-in-jquery-1.4.3.md"
---
# Return false has changed in jquery 1.4.3
The behavior of return false has changed in jQuery 1.4.3. This blog discusses
what changed.
- Author: Neeraj Singh
- Published: October 25, 2010
- Categories: jQuery
jQuery 1.4.3 was recently
[released](http://blog.jquery.com/2010/10/16/jquery-143-released/). If you
upgrade to jQuery 1.4.3 you will notice that the behavior of `return false` has
changed in this version. First let's see what `return false` does.
## return false
```javascript
$("a").click(function () {
console.log("clicked");
return false;
});
```
First ensure that above code is executed on domready. Now if I click on any link
then two things will happen.
```plaintext
e.preventDefault() will be called .
e.stopPropagation() will be called .
```
## e.preventDefault()
As the name suggests, calling `e.preventDefault()` will make sure that the
default behavior is not executed.
```plaintext
click me
```
If above link is clicked then the default behavior of the browser is to take you
to `www.google.com`. However by invoking `e.preventDefault()` browser will not
go ahead with default behavior and I will not be taken to
`www.google.com`.
## e.stopPropagation
When a link is clicked then an event "click event" is created. And this event
bubbles all the way up to the top. By invoking `e.stopPropagation` I am asking
browser to not to propagate the event. In other words the event will stop
bubbling.
```html
```
If I click on "click me" then "click event" will start bubbling. Now let's say
that I catch this event at `.two` and if I call `e.stopPropagation()` then this
event will never reach to `.first` .
## e.stopImmediatePropagation
First note that you can bind more than one event to an element. Take a look at
following case.
```html
one
```
I am going to bind three events to the above element.
```javascript
$("a").bind("click", function (e) {
console.log("first");
});
$("a").bind("click", function (e) {
console.log("second");
e.stopImmediatePropagation();
});
$("a").bind("click", function (e) {
console.log("third");
});
```
In this case there are three events bound to the same element. Notice that
second event binding invokes `e.stopImmediatePropagation()` . Calling
`e.stopImmediatePropagation` does two things.
Just like `stopPropagation` it will stop the bubbling of the event. So any
parent of this element will not get this event.
However `stopImmdiatePropagation` stops the event bubbling even to the siblings.
It kills the event right then and there. That's it. End of the event.
Once again calling `stopPropagation` means stop this event going to parent. And
calling `stopImmediatePropagation` means stop passing this event to other event
handlers bound to itself.
If you are interested
[here is link to ](http://www.w3.org/TR/2006/WD-DOM-Level-3-Events-20060413/events.html#Events-Event-stopImmediatePropagation)
DOM Level 3 Events spec.
## Back to original problem
Now that I have described what `preventDefault`, `stopPropagation` and
`stopImmediatePropagation` does lets see what changed in jQuery 1.4.3.
In jQuery 1.4.2 when I execute "return false" then that action was same as
executing:
```javascript
e.preventDefault();
e.stopPropagation();
e.stopImmediatePropagation();
```
Now `e.stopImmediatePropagation` internally calls `e.stopPragation` but I have
added here for visual clarity.
Fact that `return false` was calling `e.stopImmeidatePropagation` was a bug. Get
that. It was a bug which got fixed in jquery 1.4.3.
So in jquery 1.4.3 `e.stopImmediatePropagation` is not called. Checkout this
piece of code from `events.js` of jquery code base.
```javascript
if (ret !== undefined) {
event.result = ret;
if (ret === false) {
event.preventDefault();
event.stopPropagation();
}
}
```
As you can see when `return false` is invoked then `e.stopImmediatePropagation`
is not called.
## It gets complicated with live and a bug in jQuery 1.4.3
To make the case complicated, jQuery 1.4.3 has a bug in which
`e.preventStopImmediatePropagation` doest not work. Here is
[a link to this bug](http://forum.jquery.com/topic/e-stopimmedidatepropagation-does-not-work-with-live-or-with-delegate)
I reported.
To understand the bug take a look at following code:
```plaintext
click me
$('a.first').live('click', function(e){
alert('hello');
e.preventDefault();
e.stopImmediatePropagation();
});
$('a.first').live('click', function(){
alert('world');
});
```
Since I am invoking `e.stopImmediatePropagation` I should never see
`alert world`. However you will see that alert if you are using jQuery 1.4.3.
You can play with it [here](http://jsbin.com/ujipi4/3#html) .
This bug has been fixed as per
[this commit](http://github.com/jquery/jquery/commit/974b5aeab7a3788ff5fb9db87b9567784e0249fc)
. Note that the commit mentioned was done after the release of jQuery 1.4.3. To
get the fix you will have to wait for jQuery 1.4.4 release or use jQuery edge.
## I am using rails.js (jquery-ujs). What do I do?
As I have shown "return false" does not work in jQuery 1.4.3 . However I would
have to like to have as much backward compatibility in `jquery-ujs` as much
possible so that the same code base works with jQuery 1.4 through 1.4.3 since
not every one upgrades immediately.
[This commit](http://github.com/rails/jquery-ujs/commit/f991faf0074487b43a061168cdbfd102ee0c182c)
should make `jquery-ujs` jquery 1.4.3 compatible.
[Many issues](http://github.com/rails/jquery-ujs/issues) have been logged at
jquery-ujs and I will take a look at all of them one by one. Please do provide
your feedback.
## Links
- [Human page](https://www.bigbinary.com/blog/return-false-in-jquery-1.4.3)