jQuery event after dom tree change - javascript

I am using jQuery events like mouseover and mouseout.
When a user fires the mouseover on the target element, this element receives a new class (with removeClass and addClass).
Then, when the mouse gets out, mouseout is fired, but the selector of the element having the mouseout event doesn't match anymore, because I changed the class.
Example :
$('span.project_unsel').mouseover(function() {
$(this).removeClass('project_unsel');
$(this).addClass('project_sel');
});
After firing the above event, class has changed and the following doesn't get fired.
$('span.project_sel').mouseout(function() {
$(this).removeClass('project_sel');
$(this).addClass('project_unsel');
});
How can I tell jQuery to "update" or "bind" again too understand this ?
Many thanks !

I would suggest doing something like this instead, to makes things less confusing:
$('span.project').hover(function() {
$(this).addClass('selected');
}, function() {
$(this).removeClass('selected');
});
That is, bind .hover to elements with the class .project, and simply add and remove the .selected class when the mouseenter (first argument) and mouseleave (second argument) events are triggered.
Take a look at .hover.

There are quite a few ways to fix this, but if you want to minimize your code changes you can just add another class to your target elements that doesn't change, then bind to that.
If you can't add an additional class for some reason, try this:
$('span.project_sel,span.project_unsel').mouseout(function() {
$(this).removeClass('project_sel').addClass('project_unsel');
}).mouseover(function() {
$(this).removeClass('project_unsel').addClass('project_sel');
});
You could also take a look at toggleClass() if you feel add/remove is inelegant.
Edit: Karim's hover solution is better than doing it via mouseout/mouseover.

Related

jQuery remove scroll listener after reach certain point [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.

.change() method with visible selector issue

I am trying to have a change method for all visible select elements.
$('.select_elements:visible').change(function() {
// function
)};
The above doesn't seem to run when I change the select element. However if I write this it seems to work.
$('.select_elements').change(function() {
if ($(this).is(':visible')) {
// function
}
)};
Can anyone explain this? It wasted years (hours) of my life...
The difference is that the first version, where :visible is in the selector, only attaches the change event handler to the select elements that are visible in the DOM when the page loads.
The latter version attaches the event handler to all select elements, then checks their visibility at the time the event was fired.
Rory McCrossan's answer is an excellent explanation of what is happening. I am answering as well to propose a more performant and (to my mind at least) idiomatic solution than checking the visibility of elements in your change handler.
$(document).on('change', '.select_elements:visible', function () {
// ...
});
This approach attaches only a single change handler to the document (you could pass it any parent of your .select_elements), which fires whenever the element that is changed matches the selector in the second argument. Since that selector is evaluated for every change event, it will also fire for visible elements that weren't visible when the handler was defined.

Keep track of changes in html table/form

What I'm trying to achieve is to keep track of any changes (e. g. user input, field added, ...) within a <table>-element.
In my specific scenario users can edit fields, add rows, add fields, remove fields and rows, select something in <select>-elements, etc.
Of course I could just attach my "change"-listener to all of those actions, but I think there must be a better way.
I tried attaching a $('#myTable tbody').change()-listener to it, but that doesn't fire...
Maybe some of you know of a way to keep track of table changes without having to subscribe to every possible user action manually?
You can use Jquery liveQuery Plugin
Below is the example for mouse over and mouse out. you can do it for all the events likewise
$('table')
.livequery(function(){
// use the helper function hover to bind a mouseover and mouseout event
$(this)
.hover(function() {
$(this).addClass('hover');
}, function() {
$(this).removeClass('hover');
});
}, function() {
// unbind the mouseover and mouseout events
$(this)
.unbind('mouseover')
.unbind('mouseout');
});
Edit: As I understand it, jQuery 1.4+ should actually support the described behavior. I'll leave the rest of my post for reference.
You can add the event to every changeable element, because that is where they are fired. However, you won't have to do it manually:
$('#myTable input, #myTable select, ...).change(...)
If, as you said, there are elements added later on, you might want to look into the .live method that allows you to bind event listeners to elements that are to be created later on.
To answer my own question:
I decided on doing it kinda like #mdsl suggested:
I now listen for changes like this:
$('#myTable tbody').on('focusout', 'input, select, checkbox', myListener);

Remove Attributes onmouseover and onmouseout

I am trying to make use of JQuery's remove attribute like this:
$('#rom-img_1').removeAttr('mouseover');
$('#rom-img_2').removeAttr('mouseout');
However, it does not remove the effects of the events as the events are still triggered on mouseover and on mouseout. I have tried adding "on" before the events names too but JQuery doesn't use it like that.
Why isn't this working and how can I remove those attributes.
This is a bit of the HTML:
<div onmouseout="$('#heart_401').css({'display':'none'});" onmouseover="$('#heart_401').css({'display':'block'});" id="row-img_11"></div>
Thanks all for any help
Never register event handlers by using onsomething in the html code. It makes your markup less readable and causes various problems (such as this not pointing to the element).
Always register them by using $(...).mouseover(function() { /* yourcode */ }) or $(...).bind('mouseover', function() { /* yourcode */ }).
Then you can easily remove the handlery by using $(...).unbind('mouseover').
Of course you can also use other handlers like click or focus instead of mouseover.
The reason why removeAttr doesn't work is that handlers aren't attributes. Internally they are turned into handlers and thus you cannot remove them by removing the attribute.
However, this might work:
$('#rom-img_1')[0].mouseover = function() {};
$('#rom-img_1')[0].mouseout = function() {};
$('#rom-img_1')
You've mis-spelled row-img_11. jQuery doesn't error this, you just get a selector result with no matches.
removeAttr of onmouseover works for me with this fixed, although you would generally want to avoid using inline event handler attributes like this.
To get and set mouseover and mouseout events in jQuery use .mouseover() and .mouseout(). Syntax as follows:
Set (remove in this case):
$("#row-img_11").mouseover("");
$("#row-img_11").mouseout("");
http://api.jquery.com/mouseover/
http://api.jquery.com/mouseout/
To apply the methods to a group of divs:
$("div:contains('row-img')").each(function() {
$(this).mouseover("");
$(this).mouseout("");
});
If you just spell the id right, it works just fine:
$('#row-img_11').removeAttr('onmouseover').removeAttr('onmouseout');

Jquery help me analyze what happened: mouseover/mouseout ok but not hover/unhover

I've been working on some code where I trigger the code on hover/unhover. Then I decided to trigger the same code also on focus/blur. Usually with hover/unhover only, I go for the usual hover comma no unhover format. But this time since I was trying to add focus/blur, I had to use bind and use this.bind with the second part too, like this:
$.fn.gogogo = function (msg) {
$(this).bind("hover focus", function(){
$("#screen").html(msg).show();
});
$(this).bind("unhover blur", function(){
$("#screen").html("").hide();
});
}
The problem was that no matter what I did, hover/unhover didn't take. I had to revert back to mouseover/mouseout like this. The code is identical except for the words hover/unhover vs. mouseover/mouseout
$.fn.gogogo = function (msg) {
$(this).bind("mouseover focus", function(){
$("#screen").html(msg).show();
});
$(this).bind("mouseout blur", function(){
$("#screen").html("").hide();
});
}
I thought hover/unhover was just the jquery abstraction of mouseover/mouseout. How come the behavior is different here: hover/unhover breaks my code, while mouseover/mouseout is ok?
thanks.
There is no event called hover.
The hover method is a convenience method that binds event handler to the mouseenter and mouseleave events.
If you open the jQuery source, you'll see that the hover method is defined like this:
hover: function(fnOver, fnOut) {
return this.mouseenter(fnOver).mouseleave(fnOut);
},
You should bind to the mouseenter and mouseleave events instead.
EDIT: The difference between mouseenter and mouseover is that mouseenter (and mouseleave) don't bubble. This means that you'll get a mouseover event if the mouse moves into any element inside the one you bound to (which is probably not what you want), whereas you'll only get a mouseenter event if the mouse entered that element itself. For an example, see the documentation.
There is no "hover" event. That's just a convenience routine.

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